Using hasTagName() instead of tagName() while checking textarea type

This is a legacy issue that uses tagName() instead of hasTagName()
to make Windows port link QualifiedNames properly. Windows doesn't
have this problem any more.

R=tkent@chromium.org

Review URL: https://codereview.chromium.org/155903002

git-svn-id: svn://svn.chromium.org/blink/trunk@166563 bbb929c8-8fbe-4397-9dbb-9b2b20218538
IDL compiler: sync Python to r166479

Python side to:
Implement a binding layer for oilpan and move Gamepad to oilpan
https://codereview.chromium.org/148553004/

Also regularize test case naming.

BUG=239771
TBR=haraken
NOTRY=true

Review URL: https://codereview.chromium.org/137953011

git-svn-id: svn://svn.chromium.org/blink/trunk@166564 bbb929c8-8fbe-4397-9dbb-9b2b20218538