Revert "Reset page scale factor to 1.0f on new page navigation." (r208942).

Revert "Reset page scale factor to 1.0f on new page navigation." (r208942).

Causing layout test failures, e.g.,

fast/frames/frame-set-rotation-hit.html [ Failure ]
fast/frames/frame-set-scaling-hit.html [ Failure ]
scrollingcoordinator/non-fast-scrollable-region-scaled-iframe.html [ Failure ]
compositing/gestures/gesture-tapHighlight-simple-scaled-document.html [
ageOnlyFailure ]
fast/repaint/fixed-in-page-scale.html [ ImageOnlyFailure ]
fast/repaint/fixed-right-in-page-scale.html [ ImageOnlyFailure ]
fast/events/touch/gesture/touch-gesture-scroll-div-scaled.html [ Failure ]
fast/events/touch/page-scaled-touch-gesture-click.html [ Failure ]

http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux/builds/13078

BUG=162482
TBR=wjmaclean

Review URL: https://codereview.chromium.org/18108002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@208946 0039d316-1c4b-4281-b951-d872f2087c98