code: function getCssPropertyValue(cssStyle, propName) {
    return genericMethodCall(
               Methods.GET_PROPERTY_VALUE, cssStyle,
               cssStyle.getPropertyValue ? 'getPropertyValue' : 'getAttribute',
               [propName]) ||
        '';
  }
docs: Provides a way cross-browser way to get a CSS value from a CSS declaration.
  @param {!CSSStyleDeclaration} cssStyle A CSS style object.
  @param {string} propName A property name.
  @return {string} Value of the property as parsed by the browser.
  @supported IE8 and newer.