refactor(compiler): generate less code for bindings to DOM elements

Detailed changes:
- remove `UNINITIALIZED`, initialize change detection fields with `undefined`.
  * we use `view.numberOfChecks === 0` now everywhere
    as indicator whether we are in the first change detection cycle
    (previously we used this only in a couple of places).
  * we keep the initialization itself as change detection get slower without it.
- remove passing around `throwOnChange` in various generated calls,
  and store it on the view as property instead.
- change generated code for bindings to DOM elements as follows:
  Before:
  ```
  var currVal_10 = self.context.bgColor;
  if (jit_checkBinding15(self.throwOnChange,self._expr_10,currVal_10)) {
    self.renderer.setElementStyle(self._el_0,'backgroundColor',((self.viewUtils.sanitizer.sanitize(jit_21,currVal_10) == null)? null: self.viewUtils.sanitizer.sanitize(jit_21,currVal_10).toString()));
    self._expr_10 = currVal_10;
  }
  var currVal_11 = jit_inlineInterpolate16(1,' ',self.context.data.value,' ');
  if (jit_checkBinding15(self.throwOnChange,self._expr_11,currVal_11)) {
    self.renderer.setText(self._text_1,currVal_11);
    self._expr_11 = currVal_11;
  }
  ```,
  After:
  ```
  var currVal_10 = self.context.bgColor;
  jit_checkRenderStyle14(self,self._el_0,'backgroundColor',null,self._expr_10,self._expr_10=currVal_10,false,jit_21);
  var currVal_11 = jit_inlineInterpolate15(1,' ',self.context.data.value,' ');
  jit_checkRenderText16(self,self._text_1,self._expr_11,self._expr_11=currVal_11,false);
  ```

Performance impact:
- None seen (checked against internal latency lab)

Part of #13651

modules/@angular/core/src/change_detection/change_detection.ts

@@ -12,7 +12,7 @@ import {IterableDifferFactory, IterableDiffers} from './differs/iterable_differs
 import {KeyValueDifferFactory, KeyValueDiffers} from './differs/keyvalue_differs';
 
 export {SimpleChanges} from '../metadata/lifecycle_hooks';
-export {SimpleChange, UNINITIALIZED, ValueUnwrapper, WrappedValue, devModeEqual, looseIdentical} from './change_detection_util';
+export {SimpleChange, ValueUnwrapper, WrappedValue, devModeEqual, looseIdentical} from './change_detection_util';
 export {ChangeDetectorRef} from './change_detector_ref';
 export {ChangeDetectionStrategy, ChangeDetectorStatus, isDefaultChangeDetectionStrategy} from './constants';
 export {CollectionChangeRecord, DefaultIterableDifferFactory} from './differs/default_iterable_differ';

modules/@angular/core/src/change_detection/change_detection_util.ts

@@ -11,10 +11,6 @@ import {isPrimitive, looseIdentical} from '../facade/lang';
 
 export {looseIdentical} from '../facade/lang';
 
-export const UNINITIALIZED = {
-  toString: () => 'CD_INIT_VALUE'
-};
-
 export function devModeEqual(a: any, b: any): boolean {
   if (isListLikeIterable(a) && isListLikeIterable(b)) {
     return areIterablesEqual(a, b, devModeEqual);
@@ -75,10 +71,15 @@ export class ValueUnwrapper {
  * @stable
  */
 export class SimpleChange {
-  constructor(public previousValue: any, public currentValue: any) {}
+  constructor(
+      public previousValue: any, public currentValue: any, _isFirstChange: boolean = false) {
+    // Store this in a non declared field
+    // to prevent a breaking change (users might have `implement`ed SimpleChange before)
+    (<any>this)._firstChange = _isFirstChange;
+  }
 
   /**
    * Check whether the new value is the first value assigned.
    */
-  isFirstChange(): boolean { return this.previousValue === UNINITIALIZED; }
+  isFirstChange(): boolean { return (<any>this)._firstChange; }
 }