[css-typed-om] Make StylePropertyMap.set work with calcs.

Currently StylePropertyMap.set doesn't actually work with calcs.
The current way to check if something is, say, a <length> is to
check its CSSStyleValue::Type. However, this doesn't return
the right value for CSSMathValues, whose types may be quite
complicated.

The correct way is to use the CSSNumericValue matching algorthms:
CSSNumericValue::MatchesLength, which also takes into account
CSSMathValues and percent hints.

This patch changes the following to make this work:

- Removed base types from CSSStyleValue::StyleValueType. A base type
  like "length" is not really a CSSStyleValue type.
- Removed unused StyleValueTypeToString.
- Changed "Percent" to "Percentage" in CSSProperties.json5 as that's
  the correct term.
- Changed make_cssom_types to use the matching algorithms from
  CSSNumericValue.

Bug: 545318
Change-Id: I16aa71a4873e9992749f0f52ba641671d109170e
Reviewed-on: https://chromium-review.googlesource.com/901002
Commit-Queue: Darren Shen <shend@chromium.org>
Reviewed-by: nainar <nainar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537206}
9 files changed