Switch to equalIgnoringASCIICase throughout modules/accessibility

BUG=627682

Review-Url: https://codereview.chromium.org/2793913007
Cr-Commit-Position: refs/heads/master@{#461858}
const AtomicString& AXObject::internalRoleName(AccessibilityRole role) {
  static const Vector<AtomicString>* internalRoleNameVector =
      createInternalRoleNameVector();

  return internalRoleNameVector->at(role);
}

const AtomicString& AXObject::internalRoleName(AccessibilityRole role) {
  static const Vector<AtomicString>* internalRoleNameVector =
      createInternalRoleNameVector();

  return internalRoleNameVector->at(role);
}
