Made assert a keyword.

lib/compiler/implementation/scanner/parser.dart

Index: lib/compiler/implementation/scanner/parser.dart
diff --git a/lib/compiler/implementation/scanner/parser.dart b/lib/compiler/implementation/scanner/parser.dart
index 72fd63b483d0aa73011f218dc9b7a6b4b3d455c5..11ff6be6d4ae8b13b7e46c0b005028e980c63539 100644
--- a/lib/compiler/implementation/scanner/parser.dart
+++ b/lib/compiler/implementation/scanner/parser.dart
@@ -1146,6 +1146,8 @@ class Parser {
       return parseBreakStatement(token);
     } else if (value === 'continue') {
       return parseContinueStatement(token);
+    } else if (value === 'assert') {
+      return parseAssertStatement(token);
     } else if (value === ';') {
       return parseEmptyStatement(token);
     } else if (value === 'const') {
@@ -2127,6 +2129,14 @@ class Parser {
     return expectSemicolon(token);
   }
 
+  Token parseAssertStatement(Token token) {
+    Token assertKeyword = token;
+    token = expect('assert', token);
+    token = parseArguments(token);
+    listener.handleAssertStatement(assertKeyword, token);
+    return expectSemicolon(token);
+  }
+
   Token parseContinueStatement(Token token) {
     assert(optional('continue', token));
     Token continueKeyword = token;