Cherry-pick: [Android WebView] Fix bugs with initial-scale between 0 and 1

Cherry-pick of chromium crrev.com/24769002

Bug: 10742856

Original description:

The fix in https://chromiumcodereview.appspot.com/23754026 missed the
case of initial-scale, so fractional values were getting clamped to
zero incorrectly. Secondly, initial-scale values should not be clamped
in WebView.

BUG=298962, 282130, 295886
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=158476

Change-Id: I75f48eaaac741e54e84696be6fce2604c3d0bf05
4 files changed