[TEMP][IVI] WebGL: Turn off MSAA.

MSAA is disabled for now and will be enabled once known issues are fixed for IVI.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1113
Enable SubpixelFontScaling by default

This should fix the weird rendering we have with Android.

It will promoted to stable in M37 : https://crbug.com/362112

BUG=XWALK-1245