Revert 236475 "Disable partial swap on Windows."

> Disable partial swap on Windows.
> 
> Partial swap may be causing some performance problems, so disable it.
> 
> BUG=313104
> 
> Review URL: https://codereview.chromium.org/79643002

TBR=jbauman@chromium.org

Review URL: https://codereview.chromium.org/82523008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236881 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236881
WebGL conformance test expectations update

Mark conformance/context/context-attribute-preserve-drawing-buffer.html as fail on mac and win/intel

BUG=322770
TEST=
TBR=bajones@chromium.org,kbr@chromium.org

Review URL: https://codereview.chromium.org/83693003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236882 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236882