Bug 1067190 - Part1: Expose function for creating SVGMatrix instances in GFX land
Bug 1067190 - Part 2: Use identity matrix for gradients with singular transform matrix
Warn about dropped tags in defineSymbol parsing

Turns out we silently swallow nested symbols, which we would've found out much earlier with such a warning.
Merge pull request #1715 from tschneidereit/parser

Warn about dropped tags in defineSymbol parsing
Bug 1063786 - Support nested symbol definitions in the SWF parser
Test behaviour of scaleX and scaleY.
Merge.
Merge pull request #1714 from tschneidereit/inverse-matrix

Bug 1067190 - Handle singular gradient transform matrices in the GFX backend
A few createGradientTests.
Merge pull request #1716 from tschneidereit/parser

Bug 1063786 - Support nested symbol definitions in the SWF parser. r=tobytailor
Faster code paths for little endian data buffer operations, and writing multiple ints and floats.
Reduces object allocation in the remoting deserializer.

Objects returned by '_readMatrix', '_readRectangle', etc. reuse objects so we must never leak references to them.
GFX frames use getters and setters for the 'matrix' property, setters copy individual members of the matrix so it is safe to assign temporary matrices. Getters return references the internal matrix so the returned value is safe to read but not write.
Add a quick description of available shortcuts to the inspector.
Default DataBuffers to default endianess.
UI improvements.
Fix type-o when reading color matrices.
Make sure to copy color transforms.
Fixes renderable text's handling of matrix and rectangle parameters.
Don't include tag.id in warning about dropped tags: since we now handle nested symbols, the id can never be anything but undefined at this point.
Warn about dropped tags in one more place