Do not ignore side effects of a type test or type cast as expression, such

runtime/vm/flow_graph_builder.h

 // 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.
 
 #ifndef VM_FLOW_GRAPH_BUILDER_H_
 #define VM_FLOW_GRAPH_BUILDER_H_
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 #include "vm/allocation.h"
@@ skipping 416 matching lines @@
   // Helpers for allocating and deallocating temporary locals on top of the
   // expression stack.
   LocalVariable* EnterTempLocalScope(Value* value);
   Definition* ExitTempLocalScope(LocalVariable* var);
 
   void BuildLetTempExpressions(LetNode* node);
 
  private:
   friend class TempLocalScope;  // For ReturnDefinition.
 
+  // Helper to drop the result value.
+  virtual void ReturnValue(Value* value) {
+    Do(new DropTempsInstr(0, value));
+  }
+
   // Specify a definition of the final result.  Adds the definition to
   // the graph, but normally overridden in subclasses.
   virtual void ReturnDefinition(Definition* definition) {
     Do(definition);
   }
 
   // Shared global state.
   FlowGraphBuilder* owner_;
 
   // Output parameters.
@@ skipping 37 matching lines @@
  private:
   // Helper to set the output state to return a Value.
   virtual void ReturnValue(Value* value) { value_ = value; }
 
   // Specify a definition of the final result.  Adds the definition to
   // the graph and returns a use of it (i.e., set the visitor's output
   // parameters).
   virtual void ReturnDefinition(Definition* definition) {
     ReturnValue(Bind(definition));
   }
-
-  virtual void BuildTypeTest(ComparisonNode* node);
-  virtual void BuildTypeCast(ComparisonNode* node);
 };
 
 
 // Translate an AstNode to a control-flow graph fragment for both its
 // effects and true/false control flow (e.g., for an expression in a test
 // context).  The resulting graph is always closed (even if it is empty)
 // Successor control flow is explicitly set by a pair of pointers to
 // TargetEntryInstr*.
 //
 // To distinguish between the graphs with only nonlocal exits and graphs
@@ skipping 48 matching lines @@
   // Output parameters.
   GrowableArray<TargetEntryInstr**> true_successor_addresses_;
   GrowableArray<TargetEntryInstr**> false_successor_addresses_;
 
   intptr_t condition_token_pos_;
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_BUILDER_H_