Add support for implicitly concatenating adjacent string literals.

frog/tree.g.dart

 // Copyright (c) 2011, 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.
 // Generated by scripts/tree_gen.py.
 
 class DirectiveDefinition extends Definition {
   Identifier name;
   List<ArgumentNode> arguments;
 
   DirectiveDefinition(this.name, this.arguments, SourceSpan span): super(span) {}
@@ skipping 351 matching lines @@
 }
 
 class LiteralExpression extends Expression {
   Value value;
 
   LiteralExpression(this.value, SourceSpan span): super(span) {}
 
   visit(TreeVisitor visitor) => visitor.visitLiteralExpression(this);
 }
 
+class StringConcatExpression extends Expression {
+  List<Expression> strings;
+
+  StringConcatExpression(this.strings, SourceSpan span): super(span) {}
+
+  visit(TreeVisitor visitor) => visitor.visitStringConcatExpression(this);
+}
+
 class StringInterpExpression extends Expression {
   List<Expression> pieces;
 
   StringInterpExpression(this.pieces, SourceSpan span): super(span) {}
 
   visit(TreeVisitor visitor) => visitor.visitStringInterpExpression(this);
 }
 
 class SimpleTypeReference extends TypeReference {
   Type type;
@@ skipping 185 matching lines @@
   visitDotExpression(DotExpression node);
 
   visitVarExpression(VarExpression node);
 
   visitThisExpression(ThisExpression node);
 
   visitSuperExpression(SuperExpression node);
 
   visitLiteralExpression(LiteralExpression node);
 
+  visitStringConcatExpression(StringConcatExpression node);
+
   visitStringInterpExpression(StringInterpExpression node);
 
   visitSimpleTypeReference(SimpleTypeReference node);
 
   visitNameTypeReference(NameTypeReference node);
 
   visitGenericTypeReference(GenericTypeReference node);
 
   visitFunctionTypeReference(FunctionTypeReference node);
 
@@ skipping 253 matching lines @@
   }
 
   void visitSuperExpression(SuperExpression node) {
     output.heading('SuperExpression', node.span);
   }
 
   void visitLiteralExpression(LiteralExpression node) {
     output.heading('LiteralExpression(' + output.toValue(node.value) + ")", node.span);
   }
 
+  void visitStringConcatExpression(StringConcatExpression node) {
+    output.heading('StringConcatExpression', node.span);
+    output.writeNodeList('strings', node.strings);
+  }
+
   void visitStringInterpExpression(StringInterpExpression node) {
     output.heading('StringInterpExpression', node.span);
     output.writeNodeList('pieces', node.pieces);
   }
 
   void visitSimpleTypeReference(SimpleTypeReference node) {
     output.heading('SimpleTypeReference(' + output.toValue(node.type) + ")", node.span);
   }
 
   void visitNameTypeReference(NameTypeReference node) {
@@ skipping 63 matching lines @@
   }
 
   void visitDeclaredIdentifier(DeclaredIdentifier node) {
     output.heading('DeclaredIdentifier', node.span);
     output.writeNode('type', node.type);
     output.writeNode('name', node.name);
     output.writeValue('isFinal', node.isFinal);
   }
 
 }