gfx: De-templatize the gfx::Point and gfx::PointF classes.
This shrinks the android ChromeShell APK by 600 bytes, and improves
performance on compositor benchmarks.
Numbers can be found here https://crbug.com/407444#c15 but the summary
is this saves about 0.1ms cpu time on the JS_FULL_SCREEN_INVALIDATION
test in the thread_times.tough_compositor_cases test suite.
This also makes it easier to read and find functions in the Point and
PointF classes for developers.
R=sky
BUG=407444
Review URL: https://codereview.chromium.org/
642343003
Cr-Commit-Position: refs/heads/master@{#300283}