Made assert a keyword.

lib/compiler/implementation/warnings.dart

Index: lib/compiler/implementation/warnings.dart
diff --git a/lib/compiler/implementation/warnings.dart b/lib/compiler/implementation/warnings.dart
index 0e57d6838e2d82d2a56089a3d60da822bc73b07b..9d00fd40836590cf7ead34a5c197dc25c50e97ec 100644
--- a/lib/compiler/implementation/warnings.dart
+++ b/lib/compiler/implementation/warnings.dart
@@ -303,6 +303,13 @@ Length: #{3}''');
   static const TOP_LEVEL_VARIABLE_DECLARED_STATIC = const MessageKind(
       "Top-level variable cannot be declared static.");
 
+  static const WRONG_NUMBER_OF_ARGUMENTS_FOR_ASSERT = const MessageKind(
+      "Wrong number of arguments to assert. Should be 1, but given #{1}.");
+
+  static const ASSERT_IS_GIVEN_NAMED_ARGUMENTS = const MessageKind(
+      "assert takes no named arguments, but given #{1}.");
+
+
   static const COMPILER_CRASHED = const MessageKind(
       "Error: The compiler crashed when compiling this element.");