Remove QualifiedName argument from most HTMLElement::create functions

This patch modifies HTMLElementFactory (and the few other callers of HTML element
creation functions) to pass a tagName only for those elements, like HTMLHeadingElement,
where HTML specifies a single DOM interface for more than one tagName.

R=abarth@chromium.org, eseidel@chromium.org
BUG=316964

Review URL: https://codereview.chromium.org/66643004

git-svn-id: svn://svn.chromium.org/blink/trunk@161742 bbb929c8-8fbe-4397-9dbb-9b2b20218538