Add --enable-true-color-rendering flag

This feature has been split off from --enable-color-correct-rendering

enable-color-correct-rendering is a tweaking of the existing color
awareness to be more consistent and robust, and will only be noticeable
on non-sRGB monitor.

enable-true-color-rendering does all blending and interpolation
operations in a physically correct linear space, and has perceptually
noticeable differences on all monitors.

TBR=achuith,avi,pdr
BUG=667433
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2530503003
Cr-Commit-Position: refs/heads/master@{#434909}
13 files changed