work around webview scale bug

Seems that on Prime and Xoom, the initial return value of
getScale() when measured at the moment the WebView's scroll
position is first determined can be quite wrong. (We heavily
rely on this value to place headers as you zoom.) So ignore
the very first report of this value.

Bug: 6218921
Change-Id: I581773204ce61d2a5601396a23f896e6ec631588
1 file changed