Function installRuntimeStylesTo

test/unit/test-extensions.js:38–43

(head)

    });

    function installRuntimeStylesTo(head) {
      const runtimeStyle = win.document.createElement('style');
      runtimeStyle.setAttribute('amp-runtime', '');
      runtimeStyle.textContent = 'a{}';
      head.appendChild(runtimeStyle);
    }

    it('should register successfully without promise', () => {
      const amp = {};