Improved optional command handling in SkParsePath::FromSVGString()
Repeating command letters are optional in SVG path data strings:
https://www.w3.org/TR/SVG/paths.html#PathData
FromSVGString() already supports this feature, but only checks for
scalars prefixes == (digit | '-' | '+').
A decimal point is also a valid scalar prefix though, so it should be
included in the test.
R=caryclark@google.com
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2339813003
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2339813003