Add forEach() to CSSVariablesMap

LayoutTests/fast/css/variables/cssom-read.html

Index: LayoutTests/fast/css/variables/cssom-read.html
diff --git a/LayoutTests/fast/css/variables/cssom-read.html b/LayoutTests/fast/css/variables/cssom-read.html
index b56cc96229d337e9293a856aa471888596bef49a..13adbef34aae85baaf314341726e833fbc1ae0e1 100644
--- a/LayoutTests/fast/css/variables/cssom-read.html
+++ b/LayoutTests/fast/css/variables/cssom-read.html
@@ -9,6 +9,14 @@ if (window.testRunner) {
 
 var pre = document.querySelector("pre");
 
+function outputItem (value, name) {
+    pre.innerText += name + ": " + value + "\n";
+}
+
+pre.innerText += "Equal variables declaration objects on multiple accesses: ";
+pre.innerText += ((pre.style.var === pre.style.var) ? "pass": "fail") + "\n";
+pre.innerText += "\n";
+
 pre.innerText += "Inline style CSS text: " + pre.style.cssText + "\n";
 pre.innerText += "\n";
 
@@ -20,6 +28,10 @@ pre.innerText += "a: " + pre.style.var.get("a") + "\n";
 pre.innerText += "b: " + pre.style.var.get("b") + "\n";
 pre.innerText += "\n";
 
+pre.innerText += "Enumerate vars:\n";
+pre.style.var.forEach(outputItem);
+pre.innerText += "\n";
+
 pre.innerText += "Access non existent var:\n";
 pre.innerText += "z: " + pre.style.var.get("z") + "\n";
 pre.innerText += "\n";
@@ -37,5 +49,9 @@ pre.innerText += "a: " + pre.style.var.get("a") + "\n";
 pre.innerText += "b: " + pre.style.var.get("b") + "\n";
 pre.innerText += "c: " + pre.style.var.get("c") + "\n";
 pre.innerText += "d: " + pre.style.var.get("d") + "\n";
+pre.innerText += "\n";
+
+pre.innerText += "Enumerate vars:\n";
+pre.style.var.forEach(outputItem);
 
 </script>