Change assert implementation to not depend on a top-level function called 'assert'.

lib/compiler/implementation/lib/core_patch.dart

Index: lib/compiler/implementation/lib/core_patch.dart
diff --git a/lib/compiler/implementation/lib/core_patch.dart b/lib/compiler/implementation/lib/core_patch.dart
index aea4c6c7c2e0df68062931c651de31cddc668398..bc3e3595f1859c9776e67caf5da1d5b84eb042c6 100644
--- a/lib/compiler/implementation/lib/core_patch.dart
+++ b/lib/compiler/implementation/lib/core_patch.dart
@@ -14,3 +14,11 @@ patch class Object {
     throw new NoSuchMethodException(this, name, args);
   }
 }
+
+/**
+ * Helper function for implementing asserts. The compiler treats this specially.

[ngeoffray, 2012/09/05 10:37:10]

Should that be in js_helper then? I don't think it belongs to a patch file, nor
it should be private.

[Lasse Reichstein Nielsen, 2012/09/05 12:51:20]

That would make sense. Will move it.

+ */
+void _assert(condition) {
+  if (condition is Function) condition = condition();
+  if (!condition) throw new AssertionError();
+}