Remove left-over compiler-code from precompiled runtime.

runtime/vm/regexp_assembler.cc

 // Copyright (c) 2014, 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/regexp_assembler.h"
 
+#include "vm/flags.h"
 #include "vm/regexp.h"
 
 namespace dart {
 
+BlockLabel::BlockLabel()
+    : block_(NULL),
+      is_bound_(false),
+      is_linked_(false),
+      pos_(-1) {
+  if (!FLAG_interpret_irregexp) {
+    // Only needed by the compiled IR backend.
+    block_ = new JoinEntryInstr(-1, -1);
+  }
+}
+
+
 RegExpMacroAssembler::RegExpMacroAssembler(Zone* zone)
   : slow_safe_compiler_(false),
     global_mode_(NOT_GLOBAL),
     zone_(zone) {
 }
 
 
 RegExpMacroAssembler::~RegExpMacroAssembler() {
 }
 
 }  // namespace dart