Revert "Enable subpixel font scaling by default"

This reverts commit d7e387e218d79c9ecb93a548a222fbb3996eaecb.

This change is making the following tests fail or time out on ChromeOS:
- TextInput_SurroundingTextChangedTest.FocusToTextContainingTextAreaByClickingCase
- TextInput_TextInputStateChangedTest.MouseClickChange
- TextInput_TextInputStateChangedTest.OpenNewTabOnloadTest
- TextInput_TextInputStateChangedTest.SwitchingAllTextInputTest

See
http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chromeos_rel/builds/33322

TBR=mvanouwerkerk@chromium.org

Review URL: https://codereview.chromium.org/309853002

git-svn-id: svn://svn.chromium.org/blink/trunk@175308 bbb929c8-8fbe-4397-9dbb-9b2b20218538