Add type inference logic for cascade expressions.

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

 // Copyright (c) 2016, 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.
 
 library fasta.body_builder;
 
 import '../fasta_codes.dart'
     show FastaMessage, codeExpectedButGot, codeExpectedFunctionBody;
 
 import '../parser/parser.dart' show FormalParameterType, MemberKind, optional;
@@ skipping 620 matching lines @@
     } else {
       return buildMethodInvocation(
           toValue(receiver), callName, arguments, charOffset);
     }
   }
 
   @override
   void beginCascade(Token token) {
     debugEvent("beginCascade");
     Expression expression = popForValue();
-    if (expression is CascadeReceiver) {
+    if (expression is KernelCascadeExpression) {
       push(expression);
       push(new VariableAccessor(this, token, expression.variable));
       expression.extend();
     } else {
-      VariableDeclaration variable =
-          new VariableDeclaration.forValue(expression);
-      push(new CascadeReceiver(variable));
+      VariableDeclaration variable = new KernelVariableDeclaration.forValue(
+          expression, functionNestingLevel);
+      push(new KernelCascadeExpression(variable));
       push(new VariableAccessor(this, token, variable));
     }
   }
 
   @override
   void endCascade() {
     debugEvent("endCascade");
     Expression expression = popForEffect();
-    CascadeReceiver cascadeReceiver = pop();
+    KernelCascadeExpression cascadeReceiver = pop();
     cascadeReceiver.finalize(expression);
     push(cascadeReceiver);
   }
 
   @override
   void handleBinaryExpression(Token token) {
     debugEvent("BinaryExpression");
     if (optional(".", token) || optional("..", token)) {
       return doDotOrCascadeExpression(token);
     }
@@ skipping 2078 matching lines @@
 
 // TODO(ahe): Shouldn't need to be an expression.
 class Label extends InvalidExpression {
   String name;
 
   Label(this.name);
 
   String toString() => "label($name)";
 }
 
-class CascadeReceiver extends Let {
-  Let nextCascade;
-
-  CascadeReceiver(VariableDeclaration variable)
-      : super(
-            variable,
-            makeLet(new VariableDeclaration.forValue(new InvalidExpression()),
-                new VariableGet(variable))) {
-    nextCascade = body;
-  }
-
-  void extend() {
-    assert(nextCascade.variable.initializer is! InvalidExpression);
-    Let newCascade = makeLet(
-        new VariableDeclaration.forValue(new InvalidExpression()),
-        nextCascade.body);
-    nextCascade.body = newCascade;
-    newCascade.parent = nextCascade;
-    nextCascade = newCascade;
-  }
-
-  void finalize(Expression expression) {
-    assert(nextCascade.variable.initializer is InvalidExpression);
-    nextCascade.variable.initializer = expression;
-    expression.parent = nextCascade.variable;
-  }
-}
-
 abstract class ContextAccessor extends FastaAccessor {
   final BuilderHelper helper;
 
   final FastaAccessor accessor;
 
   final Token token;
 
   ContextAccessor(this.helper, this.token, this.accessor);
 
   @override
@@ skipping 403 matching lines @@
     if (starToken == null) {
       return AsyncMarker.Async;
     } else {
       assert(identical(starToken.stringValue, "*"));
       return AsyncMarker.AsyncStar;
     }
   } else {
     return internalError("Unknown async modifier: $asyncToken");
   }
 }