Switch to equalIgnoringASCIICase throughout modules/accessibility

BUG=627682

Review-Url: https://codereview.chromium.org/2793913007
Cr-Commit-Position: refs/heads/master@{#461858}
bool AXObject::isARIAControl(AccessibilityRole ariaRole) {
  return isARIAInput(ariaRole) || ariaRole == ButtonRole ||
         ariaRole == ComboBoxRole || ariaRole == SliderRole;
}

bool AXObject::isARIAControl(AccessibilityRole ariaRole) {
  return isARIAInput(ariaRole) || ariaRole == ButtonRole ||
         ariaRole == ComboBoxRole || ariaRole == SliderRole;
}
