Fix: iron-meta not being created in chrome 60

[admwx7]

Turns out that _meta is not getting created with the definition for iron-meta in chrome 60.

This might address #105 as well.

@stramel will follow up with an update to travis to get it running in chrome 60.

[googlebot]

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[stramel]

@e111077 @bicknellr PTAL

[notwaldorf]

Is this to fix #109? If so, the problem is something in the webcomponents polyfill, not the element itself

[stramel]

@notwaldorf I couldn't get it to pass shady dom with 1.0.6 or 1.0.7 running through polymer serve on https://github.com/MaritzSTL/mtz-update-password. However, travis ran it headless and it passed. Not sure if the webcomponents polyfill fixed it or not?