Switch to equalIgnoringASCIICase throughout modules/accessibility

BUG=627682

Review-Url: https://codereview.chromium.org/2793913007
Cr-Commit-Position: refs/heads/master@{#461858}
bool AXNodeObject::isRichlyEditable() const {
  return hasContentEditableAttributeSet();
}

bool AXNodeObject::isRichlyEditable() const {
  return hasContentEditableAttributeSet();
}
