perf($parse): use valueOf to convert objects to primitives if possible

Author: IgorMinar

src/ng/parse.js

@@ -1087,20 +1087,20 @@ function $ParseProvider() {
       if (o1 == null || o2 == null) return o1 === o2; // null/undefined
 
       if (typeof o1 === "object") {
-        // The same object is not supported because it may have been mutated
-        if (o1 === o2) return false;
 
-        if (typeof o2 !== "object") return false;
+        // attempt to convert the value to a primitive type
+        // TODO(docs): add a note to docs that by implementing valueOf even objects and arrays can
+        //             be cheaply dirty-checked
+        o1 = o1.valueOf();
 
-        // Dates
-        if (isDate(o1) && isDate(o2)) { // TODO(perf): make this more generic via valueOf
-          o1 = o1.getTime();
-          o2 = o2.getTime();
-          // Fallthru to the primitive equality check
-        } else {
+        if (typeof o1 === "object") {
           // objects/arrays are not supported - deep-watching them would be too expensive
           return false;
         }
+
+        o2 = o2.valueOf();
+
+        // fall-through to the primitive equality check
       }
 
       //Primitive or NaN