Switch to equalIgnoringASCIICase throughout modules/accessibility

BUG=627682

Review-Url: https://codereview.chromium.org/2793913007
Cr-Commit-Position: refs/heads/master@{#461858}
AXObject* AXNodeObject::rawNextSibling() const {
  if (!getNode())
    return 0;

  Node* nextSibling = getNode()->nextSibling();
  if (!nextSibling)
    return 0;

  return axObjectCache().getOrCreate(nextSibling);
}

AXObject* AXNodeObject::rawNextSibling() const {
  if (!getNode())
    return 0;

  Node* nextSibling = getNode()->nextSibling();
  if (!nextSibling)
    return 0;

  return axObjectCache().getOrCreate(nextSibling);
}
