Bug 851416 - Ensure SVGRootRenderingObserver always gets added back to the rendering observer list. r=dholbert

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extra : rebase_source : e945338503a9dbaf2ad4b4925c8f8993555e605c
Bug 849367 (part 2) - Replace the binary-expression part of the JS parser with a shift-reduce parser.  Less code, and faster.  r=njn.

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extra : rebase_source : e5d44ef33f300d8c3f979caa58c3ed332a95088c