fix($parse): ensure CSP assignable expressions have assign()

Fixes regression where the `assign()` method was not added to chains of identifiers in CSP mode,
introduced originally in b3b476d.

Closes #9048

Author: caitp

src/ng/parse.js

@@ -897,7 +897,7 @@ function getterFn(path, options, fullExp) {
     if (pathKeysLength < 6) {
       fn = cspSafeGetterFn(pathKeys[0], pathKeys[1], pathKeys[2], pathKeys[3], pathKeys[4], fullExp);
     } else {
-      fn = function(scope, locals) {
+      fn = function cspSafeGetter(scope, locals) {
         var i = 0, val;
         do {
           val = cspSafeGetterFn(pathKeys[i++], pathKeys[i++], pathKeys[i++], pathKeys[i++],
@@ -926,14 +926,14 @@ function getterFn(path, options, fullExp) {
     var evaledFnGetter = new Function('s', 'l', code); // s=scope, l=locals
     /* jshint +W054 */
     evaledFnGetter.toString = valueFn(code);
-    evaledFnGetter.assign = function(self, value) {
-      return setter(self, path, value, path);
-    };
 
     fn = evaledFnGetter;
   }
 
   fn.sharedGetter = true;
+  fn.assign = function(self, value) {
+    return setter(self, path, value, path);
+  };
   getterFnCache[path] = fn;
   return fn;
 }