Fix tests to be compatible with Android scale initialization.

On Android, we never want to allow zooming out further than the
content size.  This behavior is currently guarded by the shrinksViewportContentToFit
WebSetting.  Fix the layout tests to be compatible with this setting in
the future by expanding their body width.  I also removed the viewportEnabled
check to activate the behavior, which was redundant.

Unit tests also need some changes to be compatible with the behavior 
to always zoom out to minimum scale on page load unless 
setPageScaleFactorLimits is called (which it always is in non-Android
content_shell).  I fixed most of them to call setPageScaleFactorLimits
and deleted WebFrameTest.setPageScaleFactorBeforeFrameHasView (which
made no sense).

These changes will help prepare for better convergence of scaling behavior
between platforms in the future.

NOTRY=true
BUG=350599

Review URL: https://codereview.chromium.org/190723007

git-svn-id: svn://svn.chromium.org/blink/trunk@173979 bbb929c8-8fbe-4397-9dbb-9b2b20218538