Stop inserting placeholders for TextArea and Input elements.

Input and TextArea elements do not require to insert placeholders
in their shadow trees. It was done before due to lagacy constrains
that are no longer the case.

BUG=222806

Review URL: https://codereview.chromium.org/13532011

git-svn-id: svn://svn.chromium.org/blink/trunk@149062 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Absolutify paths to rendering/mathml/ and rendering/style/.

BUG=234793
TBR=abarth

Review URL: https://codereview.chromium.org/14407004

git-svn-id: svn://svn.chromium.org/blink/trunk@149063 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Absolutify paths to rendering/svg/.

BUG=234793
TBR=abarth

Review URL: https://codereview.chromium.org/14487005

git-svn-id: svn://svn.chromium.org/blink/trunk@149064 bbb929c8-8fbe-4397-9dbb-9b2b20218538