Fix some type warnings.

lib/compiler/implementation/ssa/nodes.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.
 
 interface HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBitAnd(HBitAnd node);
   R visitBitNot(HBitNot node);
   R visitBitOr(HBitOr node);
   R visitBitXor(HBitXor node);
@@ skipping 737 matching lines @@
   HType combine(HType other) {
     if (other.isNonPrimitive()) {
       HNonPrimitiveType temp = other;
       if (this.type === temp.type) return this;
     }
     if (other.isUnknown()) return this;
     return HType.CONFLICTING;
   }
 
   String toString() => type.toString();
-  Element lookupMember(SourceString name) => type.element.lookupMember(name);
+  Element lookupMember(SourceString name) {
+    ClassElement classElement = type.element;
+    classElement.lookupMember(name);
+  }
 }
 
 class HInstruction implements Hashable {
   Element sourceElement;
 
   final int id;
   static int idCounter;
 
   final List<HInstruction> inputs;
   final List<HInstruction> usedBy;
@@ skipping 1528 matching lines @@
   final bool isAnd;
   final SubExpression left;
   final SubExpression right;
   final HBasicBlock joinBlock;
   HAndOrBlockInformation(this.isAnd,
                          this.left,
                          this.right,
                          this.joinBlock);
   bool accept(HBlockInformationVisitor visitor) => visitor.visitAndOrInfo(this);
 }