Switch to equalIgnoringASCIICase throughout modules/accessibility

BUG=627682

Review-Url: https://codereview.chromium.org/2793913007
Cr-Commit-Position: refs/heads/master@{#461858}
FrameView* AXLayoutObject::documentFrameView() const {
  if (!getLayoutObject())
    return nullptr;

  return getLayoutObject()->document().view();
}

FrameView* AXLayoutObject::documentFrameView() const {
  if (!getLayoutObject())
    return nullptr;

  return getLayoutObject()->document().view();
}
