Bypass css text (#2811)

* [DOM mocks] enable setting element.style

* Use the style setter directly

test-utils/domMock.js

@@ -346,9 +346,8 @@ module.exports = function(options) {
 					get style() {
 						return style
 					},
-					set style(_){
-						// https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/style#Setting_style
-						throw new Error("setting element.style is not portable")
+					set style(value){
+						this.style.cssText = value
 					},
 					get className() {
 						return this.attributes["class"] ? this.attributes["class"].value : ""

test-utils/tests/test-domMock.js

@@ -665,16 +665,13 @@ o.spec("domMock", function() {
 			o(div.style.background).equals("url('/*foo*/')")
 
 		})
-		o("setting style throws", function () {
+		o("setting style updates style.cssText", function () {
 			var div = $document.createElement("div")
-			var err = false
-			try {
-				div.style = ""
-			} catch (e) {
-				err = e
-			}
+			div.style = "background: red;"
+
+			o(div.style.background).equals("red")
+			o(div.style.cssText).equals("background: red;")
 
-			o(err instanceof Error).equals(true)
 		})
 	})
 	o.spec("events", function() {