Rework SVG path normalization code

Rework SVG path normalization code

This CL moves normalization code from the SVGPathParser::emit* methods,
into a emitSegment method on a new helper object NormalizingConsumer.
Normalization is a fairly uniform process, and with a more uniform
datastructure to work on (PathSegmentData), it can be simplified.
The new NormalizingConsumer::emitSegment accepts a non-normalized
segment, which it maps to a normalized segment in a few steps:
  1) Convert relative points to absolute.
  2) Convert smooth/quadratic/arc parametrizations to cubics.
  3) Convert non-normalized verbs to normalized.
  4) Update normalization state.

Normalization state (currentPoint, subPathPoint, etc.) is also moved to
the new helper class. The coordinate mode (SVGPathParser::m_mode) is no
longer needed and removed.
The checks for quadratic/cubic curve classes are turned into functions.

BUG=467592
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192445

[fs, 2015-03-24 12:08:06]

fs@opera.com changed reviewers:
+ fmalita@chromium.org, kouhei@chromium.org, pdr@chromium.org,
schenney@chromium.org

[Stephen Chennney, 2015-03-24 15:33:39]

lgtm

[kouhei (in TOK), 2015-03-24 16:16:38]

lgtm

[fs, 2015-03-24 16:20:03]

The CQ bit was checked by fs@opera.com

[commit-bot: I haz the power, 2015-03-24 16:20:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1033643003/1

[commit-bot: I haz the power, 2015-03-24 16:24:11]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=192445