Switch to equalIgnoringASCIICase throughout modules/accessibility

BUG=627682

Review-Url: https://codereview.chromium.org/2793913007
Cr-Commit-Position: refs/heads/master@{#461858}
  void addBoolAttribute(AXBoolAttribute attribute, bool value) {
  }

  void addBoolAttribute(AXBoolAttribute attribute, bool value) {
  }
