Precompilation: drop the const object cache.

runtime/vm/precompiler.cc

 // Copyright (c) 2015, 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.
 
 #include "vm/precompiler.h"
 
 #include "vm/cha.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
 #include "vm/hash_table.h"
@@ skipping 114 matching lines @@
               " %" Pd " dynamic selectors.\n Dropped %" Pd " functions, %" Pd
               " fields.\n",
               function_count_,
               class_count_,
               selector_count_,
               dropped_function_count_,
               dropped_field_count_);
   }
 
   I->set_compilation_allowed(false);
+  I->object_store()->set_compile_time_constants(Array::null_array());
 }
 
 
 void Precompiler::ClearAllCode() {
   class ClearCodeFunctionVisitor : public FunctionVisitor {
     void VisitFunction(const Function& function) {
       function.ClearCode();
     }
   };
   ClearCodeFunctionVisitor visitor;
@@ skipping 1057 matching lines @@
       cls = it.GetNextClass();
       if (cls.IsDynamicClass()) {
         continue;  // class 'dynamic' is in the read-only VM isolate.
       }
       cls.set_is_allocated(false);
     }
   }
 }
 
 }  // namespace dart