Move buildMethodInvocation to BodyBuilder.

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 2758 matching lines @@
     }
     for (Expression argument in expressions.reversed) {
       expression = new Let(
           new VariableDeclaration.forValue(argument, isFinal: true),
           expression);
     }
     return expression;
   }
 
   @override
+  Expression buildMethodInvocation(
+      Expression receiver, Name name, Arguments arguments, int offset,
+      {bool isConstantExpression: false, bool isNullAware: false}) {
+    if (isNullAware) {
+      VariableDeclaration variable = new VariableDeclaration.forValue(receiver);
+      return makeLet(
+          variable,
+          new ConditionalExpression(
+              buildIsNull(new VariableGet(variable)),
+              new NullLiteral(),
+              new MethodInvocation(new VariableGet(variable), name, arguments)
+                ..fileOffset = offset,
+              const DynamicType()));
+    } else {
+      return new KernelMethodInvocation(receiver, name, arguments)
+        ..fileOffset = offset;
+    }
+  }
+
+  @override
   void addCompileTimeErrorFromMessage(FastaMessage message) {
     library.addCompileTimeError(message.charOffset, message.message,
         fileUri: message.uri);
   }
 
   @override
   void debugEvent(String name) {
     // printEvent(name);
   }
 
@@ skipping 460 matching lines @@
     if (starToken == null) {
       return AsyncMarker.Async;
     } else {
       assert(identical(starToken.stringValue, "*"));
       return AsyncMarker.AsyncStar;
     }
   } else {
     return internalError("Unknown async modifier: $asyncToken");
   }
 }