Port and integrate the irregexp engine from V8

runtime/vm/flow_graph_optimizer.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_OPTIMIZER_H_
 #define VM_FLOW_GRAPH_OPTIMIZER_H_
 
 #include "vm/intermediate_language.h"
 #include "vm/flow_graph.h"
 
@@ skipping 126 matching lines @@
                                          intptr_t cid,
                                          Definition* str,
                                          Definition* index,
                                          Instruction* cursor);
 
   bool InlineStringCodeUnitAt(Instruction* call,
                               intptr_t cid,
                               TargetEntryInstr** entry,
                               Definition** last);
 
+  Definition* PrepareInlineStringIndexOpUnchecked(Instruction* call,
+                                                  intptr_t cid,
+                                                  intptr_t count,
+                                                  Definition* str,
+                                                  Definition* index,
+                                                  Instruction* cursor);
+
+  bool InlineStringCodeUnitsAt(Instruction* call,
+                               intptr_t cid,
+                               intptr_t count,
+                               TargetEntryInstr** entry,
+                               Definition** last);
+
   bool InlineStringBaseCharAt(Instruction* call,
                               intptr_t cid,
                               TargetEntryInstr** entry,
                               Definition** last);
 
   bool InlineDoubleOp(Token::Kind op_kind,
                       Instruction* call,
                       TargetEntryInstr** entry,
                       Definition** last);
 
@@ skipping 347 matching lines @@
 // Optimize spill stores inside try-blocks by identifying values that always
 // contain a single known constant at catch block entry.
 class TryCatchAnalyzer : public AllStatic {
  public:
   static void Optimize(FlowGraph* flow_graph);
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_OPTIMIZER_H_