Revert "Add security checks to DOMDataStore::getWrapperForMainWorld."

This reverts revision 155678 which caused perf regression (see bug).

BUG=270213
TBR=dcarney

Review URL: https://codereview.chromium.org/22646006

git-svn-id: svn://svn.chromium.org/blink/trunk@155829 bbb929c8-8fbe-4397-9dbb-9b2b20218538