Remove unused isRecognizedTagName() in HTMLObjectElement.cpp.

This is a followup patch for r160990, and fix Linux build.

BUG=313292
TBR=ch.dumez@samsung.com

Review URL: https://codereview.chromium.org/53813002

git-svn-id: svn://svn.chromium.org/blink/trunk@160991 bbb929c8-8fbe-4397-9dbb-9b2b20218538