DevTools: move front-end URL handling to DevToolsUIBindingds

BUG=662859

Review-Url: https://codereview.chromium.org/2607833002
Cr-Commit-Position: refs/heads/master@{#440926}
int DevToolsEventForwarder::CombineKeyCodeAndModifiers(int key_code,
                                                       int modifiers) {
  return key_code | (modifiers << 16);
}

int DevToolsEventForwarder::CombineKeyCodeAndModifiers(int key_code,
                                                       int modifiers) {
  return key_code | (modifiers << 16);
}
