Send early ShowPress on TapDown when page isn't scrollable/pinchable.

LayoutTests/fast/events/touch/gesture/gesture-tap-down-scroll-pinch-expected.txt

+Gestures go here
+Gestures go here
+Tests gesture tapdown behaviour on different scroll / pinch settings.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+See http://crbug.com/316974 for details
+
+Verify hover, active aren't initially set (scroll disabled, pinch enabled).
+PASS isBoxDefault('box') is true
+tapdown on element should not activate.
+PASS isBoxDefault('box') is true
+showpress on element should activate.
+PASS isBoxHoverActive('box') is true
+Verify hover, active aren't initially set (scroll disabled, pinch disabled).
+PASS isBoxDefault('box') is true
+tapdown on element should activate.
+PASS isBoxHoverActive('box') is true
+showpress on element should keep hover and active.
+PASS isBoxHoverActive('box') is true
+Verify hover, active aren't initially set (overflowBox with scrollable ancestor).
+PASS isBoxDefault('overflowBox') is true
+tapdown on element should not activate.
+PASS isBoxDefault('overflowBox') is true
+showpress on element should activate.
+PASS isBoxHoverActive('overflowBox') is true
+Verify hover, active aren't initially set (scroll enabled, pinch disabled).
+PASS isBoxDefault('box') is true
+tapdown on element should not activate.
+PASS isBoxDefault('box') is true
+showpress on element should activate.
+PASS isBoxHoverActive('box') is true
+PASS successfullyParsed is true
+
+TEST COMPLETE
+