diff --git a/sdk/tests/conformance2/renderbuffers/framebuffer-object-attachment.html b/sdk/tests/conformance2/renderbuffers/framebuffer-object-attachment.html
index 754ff2cc73..bc4d623446 100644
--- a/sdk/tests/conformance2/renderbuffers/framebuffer-object-attachment.html
+++ b/sdk/tests/conformance2/renderbuffers/framebuffer-object-attachment.html
@@ -111,9 +111,10 @@
     gl.deleteFramebuffer(fbo);
 }
 
-function testDepthStencilAttachmentBehaviors() {
+function testDepthStencilAttachmentBehaviors(testOrphanedRenderbuffers) {
+    let suffix = testOrphanedRenderbuffers ? " with deleted renderbuffer" : "";
     debug("");
-    debug("Checking ES3 DEPTH_STENCIL_ATTACHMENT behaviors are implemented for WebGL 2");
+    debug("Checking ES3 DEPTH_STENCIL_ATTACHMENT behaviors are implemented for WebGL 2" + suffix);
     // DEPTH_STENCIL_ATTACHMENT is treated as an independent attachment point in WebGL 1;
     // however, in WebGL 2, it is treated as an alias for DEPTH_ATTACHMENT + STENCIL_ATTACHMENT.
     var size = 16;
@@ -127,24 +128,45 @@
     gl.renderbufferStorage(gl.RENDERBUFFER, gl.RGBA8, size, size);
     checkFramebuffer([gl.FRAMEBUFFER_COMPLETE]);
 
-    var depthBuffer = gl.createRenderbuffer();
-    gl.bindRenderbuffer(gl.RENDERBUFFER, depthBuffer);
-    gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, size, size);
+    function createDepthBuffer() {
+        let buffer = gl.createRenderbuffer();
+        gl.bindRenderbuffer(gl.RENDERBUFFER, buffer);
+        gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, size, size);
+        gl.bindRenderbuffer(gl.RENDERBUFFER, null);
+        return buffer;
+    }
+
+    function createStencilBuffer() {
+        let buffer = gl.createRenderbuffer();
+        gl.bindRenderbuffer(gl.RENDERBUFFER, buffer);
+        gl.renderbufferStorage(gl.RENDERBUFFER, gl.STENCIL_INDEX8, size, size);
+        gl.bindRenderbuffer(gl.RENDERBUFFER, null);
+        return buffer;
+    }
 
-    var stencilBuffer = gl.createRenderbuffer();
-    gl.bindRenderbuffer(gl.RENDERBUFFER, stencilBuffer);
-    gl.renderbufferStorage(gl.RENDERBUFFER, gl.STENCIL_INDEX8, size, size);
+    function createDepthStencilBuffer() {
+        let buffer = gl.createRenderbuffer();
+        gl.bindRenderbuffer(gl.RENDERBUFFER, buffer);
+        gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_STENCIL, size, size);
+        gl.bindRenderbuffer(gl.RENDERBUFFER, null);
+        return buffer;
+    }
 
-    var depthStencilBuffer = gl.createRenderbuffer();
-    gl.bindRenderbuffer(gl.RENDERBUFFER, depthStencilBuffer);
-    gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_STENCIL, size, size);
+    function orphan(renderbuffer) {
+        gl.bindFramebuffer(gl.FRAMEBUFFER, null);
+        gl.deleteRenderbuffer(renderbuffer);
+        gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
+    }
 
     wtu.glErrorShouldBe(gl, gl.NO_ERROR);
 
     debug("");
-    debug("color + depth");
+    debug("color + depth" + suffix);
+    var depthBuffer = createDepthBuffer();
     gl.framebufferRenderbuffer(
         gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, depthBuffer);
+    if (testOrphanedRenderbuffers)
+        orphan(depthBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", null);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", null);
@@ -153,9 +175,12 @@
     checkBufferBits(gl.DEPTH_ATTACHMENT);
 
     debug("");
-    debug("color + depth + stencil: depth != stencil");
+    debug("color + depth + stencil: depth != stencil" + suffix);
+    var stencilBuffer = createStencilBuffer();
     gl.framebufferRenderbuffer(
         gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.RENDERBUFFER, stencilBuffer);
+    if (testOrphanedRenderbuffers)
+        orphan(stencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", stencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", null);
@@ -170,9 +195,12 @@
     wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION);
 
     debug("");
-    debug("color + depth: DEPTH_STENCIL for DEPTH_ATTACHMENT");
+    debug("color + depth: DEPTH_STENCIL for DEPTH_ATTACHMENT" + suffix);
+    var depthStencilBuffer = createDepthStencilBuffer();
     gl.framebufferRenderbuffer(
         gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, depthStencilBuffer);
+    if (testOrphanedRenderbuffers)
+        orphan(depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", null);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", null);
@@ -181,9 +209,16 @@
     checkBufferBits(gl.DEPTH_ATTACHMENT);
 
     debug("");
-    debug("color + depth + stencil: DEPTH_STENCIL for DEPTH_ATTACHMENT and STENCIL_ATTACHMENT");
+    debug("color + depth + stencil: DEPTH_STENCIL for DEPTH_ATTACHMENT and STENCIL_ATTACHMENT" + suffix);
+    if (testOrphanedRenderbuffers) {
+        depthStencilBuffer = createDepthStencilBuffer();
+        gl.framebufferRenderbuffer(
+            gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, depthStencilBuffer);
+    }
     gl.framebufferRenderbuffer(
         gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.RENDERBUFFER, depthStencilBuffer);
+    if (testOrphanedRenderbuffers)
+        orphan(depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
@@ -192,7 +227,7 @@
     checkBufferBits(gl.DEPTH_STENCIL_ATTACHMENT);
 
     debug("");
-    debug("color + depth_stencil");
+    debug("color + depth_stencil" + suffix);
     var texture = gl.createTexture();
     gl.bindTexture(gl.TEXTURE_2D, texture);
     gl.texImage2D(gl.TEXTURE_2D, 0, gl.DEPTH24_STENCIL8, size, size, 0, gl.DEPTH_STENCIL, gl.UNSIGNED_INT_24_8, null);
@@ -209,8 +244,12 @@
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", null);
     wtu.glErrorShouldBe(gl, gl.NO_ERROR);
 
+    if (testOrphanedRenderbuffers)
+        depthStencilBuffer = createDepthStencilBuffer();
     gl.framebufferRenderbuffer(
         gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.RENDERBUFFER, depthStencilBuffer);
+    if (testOrphanedRenderbuffers)
+        orphan(depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
@@ -219,16 +258,24 @@
     checkBufferBits(gl.DEPTH_STENCIL_ATTACHMENT);
 
     debug("");
-    debug("DEPTH_STENCIL_ATTACHMENT overwrites DEPTH_ATTACHMENT/STENCIL_ATTACHMENT")
+    debug("DEPTH_STENCIL_ATTACHMENT overwrites DEPTH_ATTACHMENT/STENCIL_ATTACHMENT" + suffix);
+    if (testOrphanedRenderbuffers)
+        depthBuffer = createDepthBuffer();
     gl.framebufferRenderbuffer(
         gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, depthBuffer);
+    if (testOrphanedRenderbuffers)
+        orphan(depthBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", null);
     wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION);
 
+    if (testOrphanedRenderbuffers)
+        depthStencilBuffer = createDepthStencilBuffer();
     gl.framebufferRenderbuffer(
         gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.RENDERBUFFER, depthStencilBuffer);
+    if (testOrphanedRenderbuffers)
+        orphan(depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
@@ -244,9 +291,13 @@
     checkBufferBits();
 
     debug("");
-    debug("STENCIL_ATTACHMENT overwrites stencil set by DEPTH_STENCIL_ATTACHMENT")
+    debug("STENCIL_ATTACHMENT overwrites stencil set by DEPTH_STENCIL_ATTACHMENT" + suffix);
+    if (testOrphanedRenderbuffers)
+        depthStencilBuffer = createDepthStencilBuffer();
     gl.framebufferRenderbuffer(
         gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.RENDERBUFFER, depthStencilBuffer);
+    if (testOrphanedRenderbuffers)
+        orphan(depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
     shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
@@ -260,6 +311,28 @@
     wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION);
     checkFramebuffer([gl.FRAMEBUFFER_COMPLETE]);
     checkBufferBits(gl.DEPTH_ATTACHMENT);
+
+    debug("");
+    debug("DEPTH_ATTACHMENT overwrites depth set by DEPTH_STENCIL_ATTACHMENT" + suffix);
+    if (testOrphanedRenderbuffers)
+        depthStencilBuffer = createDepthStencilBuffer();
+    gl.framebufferRenderbuffer(
+        gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.RENDERBUFFER, depthStencilBuffer);
+    if (testOrphanedRenderbuffers)
+        orphan(depthStencilBuffer);
+    shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
+    shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
+    shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
+    wtu.glErrorShouldBe(gl, gl.NO_ERROR);
+
+    gl.framebufferRenderbuffer(
+        gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, null);
+    shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", null);
+    shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", depthStencilBuffer);
+    shouldEvaluateTo("gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)", null);
+    wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION);
+    checkFramebuffer([gl.FRAMEBUFFER_COMPLETE]);
+    checkBufferBits(gl.STENCIL_ATTACHMENT);
 }
 
 function testFramebufferIncompleteAttachment() {
@@ -469,7 +542,8 @@
 shouldBeNonNull("gl = wtu.create3DContext(undefined, undefined, 2)");
 
 testFramebufferWebGL1RequiredCombinations();
-testDepthStencilAttachmentBehaviors();
+testDepthStencilAttachmentBehaviors(false);
+testDepthStencilAttachmentBehaviors(true);
 testFramebufferIncompleteAttachment();
 testFramebufferIncompleteMissingAttachment();
 testFramebufferWithImagesOfDifferentSizes();