Use one offsets table per generated irregexp matching function.

runtime/vm/regexp_assembler.h

Index: runtime/vm/regexp_assembler.h
diff --git a/runtime/vm/regexp_assembler.h b/runtime/vm/regexp_assembler.h
index 92a7f28dd382f62a953e3edbf1d85458514f2692..3e2ac74c0eefde4407bdfe0f06985c235f76d3ab 100644
--- a/runtime/vm/regexp_assembler.h
+++ b/runtime/vm/regexp_assembler.h
@@ -333,9 +333,10 @@ class IRRegExpMacroAssembler: public RegExpMacroAssembler {
   intptr_t num_stack_locals() const { return local_id_.Count(); }
   intptr_t num_blocks() const { return block_id_.Count(); }
 
-  // A table mapping block ids to block offsets, used to look up offsets
-  // for indirect goto instructions.
-  void FinalizeBlockOffsetTable();
+  // Fill in the table mapping block ids to block offsets. Used to
+  // look up offsets for the computed indirect-goto instructions.
+  static void FinalizeBlockOffsetTable(Isolate* isolate,
+                                       GraphEntryInstr* graph);
 
   // Fill in indirect goto successors.
   void FinalizeIndirectGotos();