Add Wall of Browser Bugs entry for #19390

https://bugzilla.mozilla.org/show_bug.cgi?id=1253468
Closes #19390
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Added colon before enumeration
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This reverts commit d0059ac2.

Node.js 5.7.1 is out with the issue fixed.

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Example pages: Remove usages of defunct .page-header class

/fyi @mdo

Note: The selector in dashboard.css that used .page-header was superfluous
    because the margin that it zeroed was already zero even without that declaration.

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JS visual tests: Remove usages of defunct .page-header class

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Travis: use node.js 5.6

This should be reverted when the next 5.x version is out.

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Removed unused markdown-it dependency

Update docs assets

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Include all grunt required files in npm package

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Wall of Browser Bugs: Update Chromium bug tracker URLs

RIP code.google.com
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Forms fixes: fieldset/legend, new .form-control-legend, accessibility advice

docs/components/alerts.md: Correct grammar
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Use iOS 9.2 in Sauce tests

Use OS X El Capitan for Sauce tests

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Use Windows 10 for Win Chrome+Firefox tests on Sauce Labs

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