VM: Fix build on GCC which requires explicit initialization of the base class

runtime/vm/intermediate_language.h

 // Copyright (c) 2013, 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 RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_
 #define RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 38 matching lines @@
 // operation for the lattice.
 class CompileType : public ZoneAllocated {
  public:
   static const bool kNullable = true;
   static const bool kNonNullable = false;
 
   CompileType(bool is_nullable, intptr_t cid, const AbstractType* type)
       : is_nullable_(is_nullable), cid_(cid), type_(type) {}
 
   CompileType(const CompileType& other)
-      : is_nullable_(other.is_nullable_),
+      : ZoneAllocated(),
+        is_nullable_(other.is_nullable_),
         cid_(other.cid_),
         type_(other.type_) {}
 
   CompileType& operator=(const CompileType& other) {
     is_nullable_ = other.is_nullable_;
     cid_ = other.cid_;
     type_ = other.type_;
     return *this;
   }
 
@@ skipping 7955 matching lines @@
   LocationSummary* Name::MakeLocationSummary(Zone* zone, bool opt) const {     \
     UNIMPLEMENTED();                                                           \
     return NULL;                                                               \
   }                                                                            \
   void Name::EmitNativeCode(FlowGraphCompiler* compiler) { UNIMPLEMENTED(); }
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_INTERMEDIATE_LANGUAGE_H_