[chromium] Add minimum/maximumPageScaleFactor API and clamp fixes

[chromium] Add minimum/maximumPageScaleFactor API and clamp fixes
https://bugs.webkit.org/show_bug.cgi?id=72463

Patch by Alexandre Elias <aelias@google.com> on 2011-11-16
Reviewed by Darin Fisher.

We need a way to read back the computed min/max page scale factor in
order to support the software path, and for some application logic
such as zooming in/out when tapping form fields.

I also added a few clamp calls that are needed in some corner cases.

* public/WebView.h:
* src/WebViewImpl.cpp:
(WebKit::WebViewImpl::setPageScaleFactor):
(WebKit::WebViewImpl::setPageScaleFactorLimits):
(WebKit::WebViewImpl::minimumPageScaleFactor):
(WebKit::WebViewImpl::maximumPageScaleFactor):
* src/WebViewImpl.h:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@100474 268f45cc-cd09-0410-ab3c-d52691b4dbfc