Use limited JavaStringBuilder implementation instead of Dart StringBuffer.

pkg/analyzer-experimental/test/generated/scanner_test.dart

 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.scanner_test;
 
 import 'dart:collection';
 import 'package:analyzer-experimental/src/generated/java_core.dart';
 import 'package:analyzer-experimental/src/generated/java_engine.dart';
 import 'package:analyzer-experimental/src/generated/java_junit.dart';
 import 'package:analyzer-experimental/src/generated/source.dart';
@@ skipping 1409 matching lines @@
 /**
  * Instances of the class {@code TokenStreamValidator} are used to validate the correct construction
  * of a stream of tokens.
  */
 class TokenStreamValidator {
   /**
    * Validate that the stream of tokens that starts with the given token is correct.
    * @param token the first token in the stream of tokens to be validated
    */
   void validate(Token token) {
-    StringBuffer builder = new StringBuffer();
+    JavaStringBuilder builder = new JavaStringBuilder();
     validateStream(builder, token);
     if (builder.length > 0) {
       JUnitTestCase.fail(builder.toString());
     }
   }
-  void validateStream(StringBuffer builder, Token token) {
+  void validateStream(JavaStringBuilder builder, Token token) {
     if (token == null) {
       return;
     }
     Token previousToken = null;
     int previousEnd = -1;
     Token currentToken = token;
     while (currentToken != null && currentToken.type != TokenType.EOF) {
       validateStream(builder, currentToken.precedingComments);
       TokenType type28 = currentToken.type;
       if (identical(type28, TokenType.OPEN_CURLY_BRACKET) || identical(type28, TokenType.OPEN_PAREN) || identical(type28, TokenType.OPEN_SQUARE_BRACKET) || identical(type28, TokenType.STRING_INTERPOLATION_EXPRESSION)) {
         if (currentToken is! BeginToken) {
-          builder.write("\r\nExpected BeginToken, found ");
-          builder.write(currentToken.runtimeType.toString());
-          builder.write(" ");
+          builder.append("\r\nExpected BeginToken, found ");
+          builder.append(currentToken.runtimeType.toString());
+          builder.append(" ");
           writeToken(builder, currentToken);
         }
       }
       int currentStart = currentToken.offset;
       int currentLength = currentToken.length;
       int currentEnd = currentStart + currentLength - 1;
       if (currentStart <= previousEnd) {
-        builder.write("\r\nInvalid token sequence: ");
+        builder.append("\r\nInvalid token sequence: ");
         writeToken(builder, previousToken);
-        builder.write(" followed by ");
+        builder.append(" followed by ");
         writeToken(builder, currentToken);
       }
       previousEnd = currentEnd;
       previousToken = currentToken;
       currentToken = currentToken.next;
     }
   }
-  void writeToken(StringBuffer builder, Token token) {
-    builder.write("[");
-    builder.write(token.type);
-    builder.write(", '");
-    builder.write(token.lexeme);
-    builder.write("', ");
-    builder.write(token.offset);
-    builder.write(", ");
-    builder.write(token.length);
-    builder.write("]");
+  void writeToken(JavaStringBuilder builder, Token token) {
+    builder.append("[");
+    builder.append(token.type);
+    builder.append(", '");
+    builder.append(token.lexeme);
+    builder.append("', ");
+    builder.append(token.offset);
+    builder.append(", ");
+    builder.append(token.length);
+    builder.append("]");
   }
 }
 abstract class AbstractScannerTest extends JUnitTestCase {
   void test_ampersand() {
     assertToken(TokenType.AMPERSAND, "&");
   }
   void test_ampersand_ampersand() {
     assertToken(TokenType.AMPERSAND_AMPERSAND, "&&");
   }
   void test_ampersand_eq() {
@@ skipping 566 matching lines @@
     listener.assertNoErrors();
     return token;
   }
 }
 main() {
   CharBufferScannerTest.dartSuite();
   KeywordStateTest.dartSuite();
   StringScannerTest.dartSuite();
   TokenTypeTest.dartSuite();
 }