fix($compile): don't run unnecessary update to one-way bindings

The watch handler was triggering on its first invocation, even though
its change had already been dealt with when setting up the binding.

Closes angular#14546

Author: petebacondarwin

test/ng/compileSpec.js

@@ -4823,12 +4823,16 @@ describe('$compile', function() {
             controller: function() {
               component = this;
               this.input = 'constructor';
+              log.push('constructor');
+
               this.$onInit = function() {
                 this.input = '$onInit';
+                log.push('$onInit');
               };
+
               this.$onChanges = function(changes) {
                 if (changes.input) {
-                  log.push(changes.input);
+                  log.push(['$onChanges', changes.input]);
                 }
               };
             }
@@ -4841,6 +4845,11 @@ describe('$compile', function() {
 
           expect($rootScope.name).toEqual('outer');
           expect(component.input).toEqual('$onInit');
+          expect(log).toEqual([
+            'constructor',
+            ['$onChanges', jasmine.objectContaining({ currentValue: 'outer' })],
+            '$onInit'
+          ]);
         });
       });