Try to not use incomplete Dart types in HType.

sdk/lib/_internal/compiler/implementation/ssa/builder.dart

 // Copyright (c) 2012, 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.
 
 part of ssa;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 230 matching lines @@
   }
 
   HType cachedTypeOfThis;
 
   HType getTypeOfThis() {
     HType result = cachedTypeOfThis;
     if (result == null) {
       Element element = closureData.thisElement;
       ClassElement cls = element.enclosingElement.getEnclosingClass();
       Compiler compiler = builder.compiler;
-      DartType type = cls.computeType(compiler);
+      // Use the raw type because we don't have the type context for the
+      // type parameters.
+      DartType type = cls.rawType;
       if (compiler.world.isUsedAsMixin(cls)) {
         // If the enclosing class is used as a mixin, [:this:] can be
         // of the class that mixins the enclosing class. These two
         // classes do not have a subclass relationship, so, for
         // simplicity, we mark the type as an interface type.
         result = new HType.nonNullSubtype(type, compiler);
       } else {
         result = new HType.nonNullSubclass(type, compiler);
       }
       cachedTypeOfThis = result;
@@ skipping 4828 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }