Bug 1065855 - Ignore updating check when setting MediaSource Duration within a SourceBuffer append - r=kinetik

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extra : rebase_source : baa31fd9d380ebf6765adb5ce89848c6dd3f4241
Bug 1065855 - Check for waiting media resources before calling ReadMetadata - r=cpearce

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extra : rebase_source : 45022c3d553e82e098908af7682cf241593b57f9
Bug 1065855 - Tests for MediaSource seekable range - r=kinetik

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extra : rebase_source : 01d29379c8e4541c72f6fcd186506ba4e9d3f28c