Merge 113095 - [chromium] Switch touchpad fling curve physics to absolute (not scaled) curve.

Merge 113095 - [chromium] Switch touchpad fling curve physics to absolute (not scaled) curve.
https://bugs.webkit.org/show_bug.cgi?id=83061

Reviewed by James Robinson.

Source/WebCore:

Revised existing unit tests.

Use an absolute curve for touchpad fling. Here we identify the location on the curve corresponding
to the initial fling velocity, and "jump in" at that point. Avoids issues around time/magnitude
scaling present in previous implementation, and gives better feel to fling animation.

* platform/TouchpadFlingPlatformGestureCurve.cpp:
(WebCore):
(WebCore::TouchpadFlingPlatformGestureCurve::create):
(WebCore::position):
(WebCore::velocity):
(WebCore::TouchpadFlingPlatformGestureCurve::TouchpadFlingPlatformGestureCurve):
(WebCore::TouchpadFlingPlatformGestureCurve::apply):
* platform/TouchpadFlingPlatformGestureCurve.h:
(TouchpadFlingPlatformGestureCurve):

Source/WebKit/chromium:

* tests/PlatformGestureCurveTest.cpp:


TBR=wjmaclean@chromium.org
BUG=121824
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=113131