Implement initializer asserts.

pkg/front_end/lib/src/fasta/fasta_codes_generated.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // NOTE: THIS FILE IS GENERATED. DO NOT EDIT.
 //
 // Instead modify 'pkg/front_end/messages.yaml' and run
 // 'pkg/front_end/tool/_fasta/generate_messages.dart' to update.
 
 part of fasta.codes;
@@ skipping 26 matching lines @@
 
 typedef FastaMessage _StackOverflow(Uri uri, int charOffset);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 FastaMessage _formatStackOverflow(Uri uri, int charOffset) {
   return new FastaMessage(uri, charOffset, codeStackOverflow,
       message: "Stack overflow.", arguments: {});
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const FastaCode<_AssertExtraneousArgument> codeAssertExtraneousArgument =
+    const FastaCode<_AssertExtraneousArgument>("AssertExtraneousArgument",
+        template: r"`assert` can't have more than two arguments.",
+        format: _formatAssertExtraneousArgument);
+
+typedef FastaMessage _AssertExtraneousArgument(Uri uri, int charOffset);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+FastaMessage _formatAssertExtraneousArgument(Uri uri, int charOffset) {
+  return new FastaMessage(uri, charOffset, codeAssertExtraneousArgument,
+      message: "`assert` can't have more than two arguments.", arguments: {});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const FastaCode<_UnexpectedToken> codeUnexpectedToken =
     const FastaCode<_UnexpectedToken>("UnexpectedToken",
         template: r"Unexpected token '#lexeme'.",
         dart2jsCode: "FASTA_FATAL",
         format: _formatUnexpectedToken);
 
 typedef FastaMessage _UnexpectedToken(Uri uri, int charOffset, Token token);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 FastaMessage _formatUnexpectedToken(Uri uri, int charOffset, Token token) {
@@ skipping 695 matching lines @@
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 FastaMessage _formatYieldAsIdentifier(Uri uri, int charOffset) {
   return new FastaMessage(uri, charOffset, codeYieldAsIdentifier,
       message:
           "'yield' can't be used as an identifier in 'async', 'async*', or 'sync*' methods.",
       arguments: {});
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const FastaCode<_AssertAsExpression> codeAssertAsExpression =
+    const FastaCode<_AssertAsExpression>("AssertAsExpression",
+        template: r"`assert` can't be used as an expression.",
+        format: _formatAssertAsExpression);
+
+typedef FastaMessage _AssertAsExpression(Uri uri, int charOffset);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+FastaMessage _formatAssertAsExpression(Uri uri, int charOffset) {
+  return new FastaMessage(uri, charOffset, codeAssertAsExpression,
+      message: "`assert` can't be used as an expression.", arguments: {});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const FastaCode<_OnlyTry> codeOnlyTry = const FastaCode<_OnlyTry>("OnlyTry",
     template:
         r"Try block should be followed by 'on', 'catch', or 'finally' block.",
     tip: r"Did you forget to add a 'finally' block?",
     dart2jsCode: "FASTA_IGNORED",
     format: _formatOnlyTry);
 
 typedef FastaMessage _OnlyTry(Uri uri, int charOffset);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
@@ skipping 152 matching lines @@
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 FastaMessage _formatNonAsciiIdentifier(
     Uri uri, int charOffset, String character, int codePoint) {
   String unicode = "(U+${codePoint.toRadixString(16).padLeft(4, '0')})";
   return new FastaMessage(uri, charOffset, codeNonAsciiIdentifier,
       message:
           "The non-ASCII character '$character' ($unicode) can't be used in identifiers, only in strings and comments.",
       tip: "Try using an US-ASCII letter, a digit, '_' (an underscore), or '\$' (a dollar sign).",
       arguments: {'character': character, 'codePoint': codePoint});
 }