Revert of Adding PreRole in blink side to expose HTML pre tag with correct MSAA+IA2. (patchset #1 id:1 of https://codereview.chromium.org/671003002/)

Reason for revert:
Broke the browser tests crbug.com/426608

Original issue's description:
> Adding PreRole in blink side to expose HTML pre tag with correct MSAA+IA2.
> 
> This is blink side CL to expose HTML pre tag in chromium side with proper MSAA+IA2 role.
> 
> BUG=426053
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=184300

TBR=dmazzoni@chromium.org,aboxhall@chromium.org,shreeram.k@samsung.com
NOTREECHECKS=true
NOTRY=true
BUG=426053

Review URL: https://codereview.chromium.org/675033002

git-svn-id: svn://svn.chromium.org/blink/trunk@184311 bbb929c8-8fbe-4397-9dbb-9b2b20218538