De-flake WebViewTest.testGetContentHeight.

The WebView can be in a state where the contents scale and height
are non-zero but the WebView's height in the Android view tree
is zero. This occurs if these values are read between the WebView
requesting a layout pass and the layout pass occurring.

BUG: 11006894
Change-Id: I53d6776dd9aed9e35b357cfffe1bc71eb7109531
1 file changed