Switch to equalIgnoringASCIICase throughout modules/accessibility

BUG=627682

Review-Url: https://codereview.chromium.org/2793913007
Cr-Commit-Position: refs/heads/master@{#461858}
AXObject* AXObjectCacheImpl::getAriaOwnedParent(const AXObject* child) const {
  return objectFromAXID(m_ariaOwnedChildToOwnerMapping.at(child->axObjectID()));
}

AXObject* AXObjectCacheImpl::getAriaOwnedParent(const AXObject* child) const {
  return objectFromAXID(m_ariaOwnedChildToOwnerMapping.at(child->axObjectID()));
}
