Removed duplicated line of code in Canvas2DLayerBridge due to merge conflict resolution error

TBR=senorblanco
BUG=240881, 226928, 237799

Review URL: https://codereview.chromium.org/19117003

git-svn-id: svn://svn.chromium.org/blink/trunk@154144 bbb929c8-8fbe-4397-9dbb-9b2b20218538