feat(code size): make assertionsEnabled() statically computable by dart2js

yjbanov · yjbanov · commit 241632aaa118 · 2015-09-16T19:01:48.000Z
Our existing implementation prevented dart2js from statically deducing the return value. This fix does not yet result in better tree-shaking due to the following dart2js bugs: dart-lang/sdk#24354 dart-lang/sdk#24355 Closes angular#4198
diff --git a/modules/angular2/src/core/facade/lang.dart b/modules/angular2/src/core/facade/lang.dart
@@ -243,17 +243,11 @@ bool isJsObject(o) {
   return false;
 }
 
-var _assertionsEnabled = null;
 bool assertionsEnabled() {
-  if (_assertionsEnabled == null) {
-    try {
-      assert(false);
-      _assertionsEnabled = false;
-    } catch (e) {
-      _assertionsEnabled = true;
-    }
-  }
-  return _assertionsEnabled;
+  // TODO(yjbanov): verify that this is inlined after https://github.com/dart-lang/sdk/issues/24355
+  bool k = false;
+  assert((k = true));
+  return k;
 }
 
 // Can't be all uppercase as our transpiler would think it is a special directive...
