feat(parser): adds basic expressions to the parser.

Mostly copy pasta from angular.dart.

Remove GetterFactory in favor for ClosureMap (which has basically the same
implementation).

modules/facade/src/lang.dart

@@ -27,6 +27,26 @@ class IMPLEMENTS {
 
 bool isPresent(obj) => obj != null;
 bool isBlank(obj) => obj == null;
+bool toBool(x) {
+  if (x is bool) return x;
+  if (x is num) return x != 0;
+  return false;
+}
+
+autoConvertAdd(a, b) {
+  if (a != null && b != null) {
+    if (a is String && b is! String) {
+      return a + b.toString();
+    }
+    if (a is! String && b is String) {
+      return a.toString() + b;
+    }
+    return a + b;
+  }
+  if (a != null) return a;
+  if (b != null) return b;
+  return 0;
+}
 
 String stringify(obj) => obj.toString();
 

modules/facade/src/lang.es6

@@ -20,6 +20,14 @@ export function isBlank(obj):boolean {
   return obj === undefined || obj === null;
 }
 
+export function toBool(obj) {
+  return !!obj;
+}
+
+export function autoConvertAdd(a, b) {
+  return a + b;
+}
+
 export function stringify(token):string {
   if (typeof token === 'string') {
     return token;