feat(ngModelOptions): allow options to be inherited from ancestor ngModelOptions

Previously, you had to apply the complete set of `ngModelOptions` at every point where
you might want to modify just one or two settings.

This change allows more general settings to be applied nearer to the top of the DOM
and then for more specific settings to override those general settings further down
in the DOM.

To prevent unwanted inheritance you must opt-in on a case by case basis:
* To inherit as single property you simply provide the special value `"$inherit"`.
* To inherit all properties not specified locally then include a property `"*": "$inherit"`.

Closes angular#10922
Closes angular#15389

BREAKING CHANGE:

The programmatic API for `ngModelOptions` has changed. You must now read options
via the `ngModelController.getOption(name)` method, rather than accessing the option directly as a property
of the `ngModelContoller.$options` object. This does not affect the usage in templates and only
affects custom directives that might have been reading options for their own purposes.

Author: petebacondarwin

src/ng/directive/ngModelOptions.js

@@ -1,30 +1,19 @@
 'use strict';
 
-var ngModelOptionsDefaults = {
-  updateOn: 'default',
-  debounce: 0,
-  getterSetter: false,
-  allowInvalid: false,
-  timezone: null
-};
-
+/* exported $defaultModelOptions */
+var $defaultModelOptions;
+var DEFAULT_REGEXP = /(\s+|^)default(\s+|$)/;
 
 /**
  * @ngdoc type
  * @name ModelOptions
  * @description
  * A container for the options set by the {@link ngModelOptions} directive
  */
-function ModelOptions(options, parentOptions) {
-  this.$$parentOptions = parentOptions;
-  this.$$options = extend({}, options); // make a shallow copy
-  this.$$extendParent();
-  defaults(this.$$options, ngModelOptionsDefaults);
-  this.$$processOptions();
+function ModelOptions(options) {
+  this.$$options = options;
 }
 
-var DEFAULT_REGEXP = /(\s+|^)default(\s+|$)/;
-
 ModelOptions.prototype = {
 
   /**
@@ -46,52 +35,50 @@ ModelOptions.prototype = {
    * @return {ModelOptions} a new `ModelOptions` object initialized with the given options.
    */
   createChild: function(options) {
-    return new ModelOptions(options, this.$$options);
-  },
-
-  $$extendParent: function() {
     var inheritAll = false;
 
+    // make a shallow copy
+    options = extend({}, options);
+
     // Inherit options from the parent if specified by the value `"$inherit"`
-    forEach(this.$$options, /* @this */function(option, key) {
+    forEach(options, /* @this */ function(option, key) {
       if (option === '$inherit') {
         if (key === '*') {
           inheritAll = true;
         } else {
-          this.$$options[key] = this.$$parentOptions[key];
+          options[key] = this.$$options[key];
         }
+      } else if (key === 'updateOn') {
+        options.updateOnDefault = false;
+        options[key] = trim(option.replace(DEFAULT_REGEXP, function() {
+          options.updateOnDefault = true;
+          return ' ';
+        }));
       }
     }, this);
 
-    // We have a property of the form: `"*": "$inherit"`
     if (inheritAll) {
-      delete this.$$options['*'];
-      defaults(this.$$options, this.$$parentOptions);
+      // We have a property of the form: `"*": "$inherit"`
+      delete options['*'];
+      defaults(options, this.$$options);
     }
-  },
 
-  $$processOptions: function() {
-    var options = this.$$options;
-    // updateOn and updateOnDefault
-    if (isDefined(options.updateOn) && options.updateOn.trim()) {
-      options.updateOnDefault = false;
-      // extract "default" pseudo-event from list of events that can trigger a model update
-      options.updateOn = trim(options.updateOn.replace(DEFAULT_REGEXP, function() {
-        options.updateOnDefault = true;
-        return ' ';
-      }));
-    } else if (this.$$parentOptions) {
-      options.updateOn = this.$$parentOptions.updateOn;
-      options.updateOnDefault = this.$$parentOptions.updateOnDefault;
-    } else {
-      options.updateOnDefault = true;
-    }
+    // Finally add in any missing defaults
+    defaults(options, $defaultModelOptions.$$options);
+
+    return new ModelOptions(options);
   }
 };
 
 
-/* exported $defaultModelOptions */
-var $defaultModelOptions = new ModelOptions(ngModelOptionsDefaults);
+$defaultModelOptions = new ModelOptions({
+  updateOn: '',
+  updateOnDefault: true,
+  debounce: 0,
+  getterSetter: false,
+  allowInvalid: false,
+  timezone: null
+});
 
 
 /**
@@ -154,7 +141,7 @@ var $defaultModelOptions = new ModelOptions(ngModelOptionsDefaults);
  * { allowInvalid: true, updateOn: 'default', debounce: 200 }
  * ```
  *
- * Notice that the `debounce` setting now inherits The value from the outer `<div>` element.
+ * Notice that the `debounce` setting now inherits the value from the outer `<div>` element.
  *
  * If you are creating a reusable component then you should be careful when using `"*": "$inherit"`
  * since you may inadvertently inherit a setting in the future that changes the behavior of your component.

test/ng/directive/ngModelOptionsSpec.js

@@ -164,6 +164,22 @@ describe('ngModelOptions', function() {
         dealoc(container);
       });
 
+      it('should correctly inherit default and another specified event for `updateOn`', function() {
+        var container = $compile(
+                  '<div ng-model-options="{updateOn: \'default blur\'}">' +
+                    '<input ng-model-options="{\'*\': \'$inherit\'}">' +
+                  '</div>')($rootScope);
+
+        var input = container.find('input');
+        var inputOptions = input.controller('ngModelOptions').$options;
+
+        expect(inputOptions.getOption('updateOn')).toEqual('blur');
+        expect(inputOptions.getOption('updateOnDefault')).toEqual(true);
+
+        dealoc(container);
+      });
+
+
       it('should make a copy of the options object', function() {
         $rootScope.options = {updateOn: 'default'};
         var inputElm = helper.compileInput(