DevTools: refine DataGrid member types.

BUG=

Review URL: https://codereview.chromium.org/398573003

git-svn-id: svn://svn.chromium.org/blink/trunk@178655 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Clarify font-weight parsing for 100-900 keywords

The current parsing for font-weight is slightly confusing as it has
branches for keywords 100 to 900 to be parsed as keywords (CSSValueID)
or numbers. These won't get parsed as keywords so we don't need to have
CSSValue100 to CSSValue900 in the range we check.

Review URL: https://codereview.chromium.org/410633002

git-svn-id: svn://svn.chromium.org/blink/trunk@178656 bbb929c8-8fbe-4397-9dbb-9b2b20218538