Redo "Use an explicit 'this' parameter instead of 'This' nodes."

tests/compiler/dart2js/backend_dart/sexpr_unstringifier.dart

Index: tests/compiler/dart2js/backend_dart/sexpr_unstringifier.dart
diff --git a/tests/compiler/dart2js/backend_dart/sexpr_unstringifier.dart b/tests/compiler/dart2js/backend_dart/sexpr_unstringifier.dart
index 3c982c744a704b6bc2c9d7301a6df76c47c8d9d3..1f06307f1fe54b0dff42421870d1c00dbf8374ce 100644
--- a/tests/compiler/dart2js/backend_dart/sexpr_unstringifier.dart
+++ b/tests/compiler/dart2js/backend_dart/sexpr_unstringifier.dart
@@ -87,7 +87,17 @@ class Tokens {
 
   String read([String expected]) {
     if (expected != null) {
-      assert(current == expected);
+      if (current != expected) {
+        print('expected "$expected", found "$current"');
+        int start = _index - 15;
+        String dotdotdot = '... ';
+        if (start < 0) {
+          start = 0;
+          dotdotdot = '';
+        }
+        print('${dotdotdot}${_list.sublist(start, _index + 1).join(' ')}');
+        assert(current == expected);
+      }
     }
     return _list[_index++];
   }
@@ -268,6 +278,20 @@ class SExpressionUnstringifier {
       element = new DummyElement(tokens.read());
     }
 
+    // (this) or ()
+    Definition thisParameter = null;
+    tokens.consumeStart();
+    if (tokens.current != ')') {
+      String thisName = tokens.read();
+      if (name2variable.containsKey(thisName)) {
+        thisParameter = name2variable[thisName];
+      } else {
+        thisParameter = new Parameter(new DummyElement(thisName));
+        name2variable[thisName] = thisParameter;
+      }
+    }
+    tokens.consumeEnd();
+
     // (parameters)
     List<Definition> parameters = <Definition>[];
     tokens.consumeStart();
@@ -292,7 +316,7 @@ class SExpressionUnstringifier {
     Expression body = parseExpression();
 
     tokens.consumeEnd();
-    return new FunctionDefinition(element, parameters,
+    return new FunctionDefinition(element, thisParameter, parameters,
         new RunnableBody(body, cont), null, null);
   }