Switch to equalIgnoringASCIICase throughout modules/accessibility

BUG=627682

Review-Url: https://codereview.chromium.org/2793913007
Cr-Commit-Position: refs/heads/master@{#461858}
AXLayoutObject::AXLayoutObject(LayoutObject* layoutObject,
                               AXObjectCacheImpl& axObjectCache)
    : AXNodeObject(layoutObject->node(), axObjectCache),
      m_layoutObject(layoutObject) {
#if DCHECK_IS_ON()
  m_layoutObject->setHasAXObject(true);
#endif
}

AXLayoutObject::AXLayoutObject(LayoutObject* layoutObject,
                               AXObjectCacheImpl& axObjectCache)
    : AXNodeObject(layoutObject->node(), axObjectCache),
      m_layoutObject(layoutObject) {
#if DCHECK_IS_ON()
  m_layoutObject->setHasAXObject(true);
#endif
}
