Change isBlock and isInline functions to check for isElementNode
Change isBlock and isInline functions to check for isElementNode

Simple refactoring to add isElementNode check in isBlock and isInline functions.
Also removed isElementNode check from enclosingBlock.

Webkit bug pointing the same - https://bugs.webkit.org/show_bug.cgi?id=86106

TEST=Refactoring, no behavior change.

Review URL: https://codereview.chromium.org/98723009

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@163285 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs