Revert "Unify logic for deciding whether m_graphicsLayer draws content."

This reverts commit 8fd53d76020acc04dccfd066375ccb59b194c8a6.

Broke:

  webkit_tests compositing/overflow/accelerated-overflow-scroll-should-not-affect-perspective.html
  webkit_tests virtual/gpu/compositedscrolling/overflow/accelerated-overflow-scroll-should-not-affect-perspective.html

On:

  WebKit Mac10.7
  WebKit Mac10.8
  WebKit Mac10.8 (retina)
  WebKit Mac10.9

BUG=409593
TBR=tkent, chrishtr, vollick

Review URL: https://codereview.chromium.org/546553002

git-svn-id: svn://svn.chromium.org/blink/trunk@181398 bbb929c8-8fbe-4397-9dbb-9b2b20218538