Don't steal the copy event (bug 1857823)

There were no specific reasons to stop the propagation of the event
and it can be useful for some third parties to catch the event to let
them do their own stuff.

test/integration/copy_paste_spec.js

@@ -145,6 +145,7 @@ describe("Copy and paste", () => {
       );
     });
   });
+
   describe("Copy/paste and ligatures", () => {
     let pages;
 
@@ -197,4 +198,52 @@ describe("Copy and paste", () => {
       );
     });
   });
+
+  describe("Copy event", () => {
+    let pages;
+
+    beforeAll(async () => {
+      pages = await loadAndWait(
+        "tracemonkey.pdf",
+        ".textLayer .endOfContent",
+        100,
+        async page => {
+          await page.waitForFunction(
+            () => !!window.PDFViewerApplication.eventBus
+          );
+          await waitForTextLayer(page);
+        }
+      );
+    });
+
+    afterAll(async () => {
+      await closePages(pages);
+    });
+
+    it("must check that the copy event is not stolen (bug 1857823)", async () => {
+      await Promise.all(
+        pages.map(async ([browserName, page]) => {
+          await page.evaluate(async () => {
+            const promise = new Promise(resolve => {
+              document.addEventListener("selectionchange", resolve, {
+                once: true,
+              });
+            });
+            const range = document.createRange();
+            const span = document.querySelector(".textLayer span");
+            range.selectNode(span);
+            const selection = window.getSelection();
+            selection.addRange(range);
+            await promise;
+          });
+
+          const promise = waitForEvent(page, "copy", 300000);
+          await page.keyboard.down("Control");
+          await page.keyboard.press("c");
+          await page.keyboard.up("Control");
+          await promise;
+        })
+      );
+    });
+  });
 });

web/text_layer_builder.js

@@ -218,17 +218,21 @@ class TextLayerBuilder {
       end.classList.remove("active");
     });
 
-    div.addEventListener("copy", event => {
-      if (!this.#enablePermissions) {
-        const selection = document.getSelection();
-        event.clipboardData.setData(
-          "text/plain",
-          removeNullCharacters(normalizeUnicode(selection.toString()))
-        );
-      }
-      event.preventDefault();
-      event.stopPropagation();
-    });
+    div.addEventListener(
+      "copy",
+      event => {
+        if (!this.#enablePermissions) {
+          const selection = document.getSelection();
+          event.clipboardData.setData(
+            "text/plain",
+            removeNullCharacters(normalizeUnicode(selection.toString()))
+          );
+        }
+      },
+      // Capture the event in order to be sure that the copy event has the
+      // correct value.
+      { capture: true, passive: true }
+    );
   }
 }