Prepare to enable RenderTextHarfBuzz by default

- Fix and partially disable the RenderText unit tests to make sure RenderTextHarfBuzz passes the tests. Call EnsureLayout() in GetGlyphBounds() since it has been made public by r252873.

- Add a "--disable-harfbuzz-rendertext" switch to make enabling RTHB by default easier.

BUG=321868
NOTRY=true

Review URL: https://codereview.chromium.org/419753002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@285761 0039d316-1c4b-4281-b951-d872f2087c98
9 files changed