revert: fix(Scope): aggressively clean up scope on $destroy to minimize leaks

This reverts commit f552f25.

The commit is causing regressions.

Closes #6897

Author: IgorMinar

src/ng/rootScope.js

@@ -731,26 +731,15 @@ function $RootScopeProvider(){
 
         forEach(this.$$listenerCount, bind(null, decrementListenerCount, this));
 
-        // sever all the references to parent scopes (after this cleanup, the current scope should
-        // not be retained by any of our references and should be eligible for garbage collection)
         if (parent.$$childHead == this) parent.$$childHead = this.$$nextSibling;
         if (parent.$$childTail == this) parent.$$childTail = this.$$prevSibling;
         if (this.$$prevSibling) this.$$prevSibling.$$nextSibling = this.$$nextSibling;
         if (this.$$nextSibling) this.$$nextSibling.$$prevSibling = this.$$prevSibling;
 
-        // This is bogus code that works around V8's memory leak coming from ICs
-        // see: https://code.google.com/p/v8/issues/detail?id=2073#c26
-        //
-        // for more info also see:
-        // - https://github.com/angular/angular.js/issues/6794#issuecomment-38648909
-        // - https://github.com/angular/angular.js/issues/1313#issuecomment-10378451
-        for (var prop in this) {
-          if (hasOwnProperty.call(this, prop)) {
-            this[prop] = null;
-          }
-        }
-        // recreate the $$destroyed flag
-        this.$$destroyed = true;
+        // This is bogus code that works around Chrome's GC leak
+        // see: https://github.com/angular/angular.js/issues/1313#issuecomment-10378451
+        this.$parent = this.$$nextSibling = this.$$prevSibling = this.$$childHead =
+            this.$$childTail = null;
       },
 
       /**