This patch is the propagation version of https://codereview.chromium.org/10824032 patch

src/assembler.h

Index: src/assembler.h
===================================================================
--- src/assembler.h	(revision 13584)
+++ src/assembler.h	(working copy)
@@ -844,6 +844,7 @@
 #ifdef ENABLE_GDB_JIT_INTERFACE
     gdbjit_lineinfo_ = NULL;
 #endif
+    jit_handler_data_ = NULL;
   }
 
 #ifdef ENABLE_GDB_JIT_INTERFACE
@@ -863,7 +864,15 @@
     return lineinfo;
   }
 #endif
+  void AttachJITHandlerData(void* user_data) {
+    jit_handler_data_ = user_data;
+  }
 
+  void* DetachJITHandlerData() {
+    void* old_data = jit_handler_data_;
+    jit_handler_data_ = NULL;
+    return old_data;
+  }
   // Set current position to pos.
   void RecordPosition(int pos);
 
@@ -879,13 +888,19 @@
     return state_.current_statement_position;
   }
 
+  Assembler* assembler() {
+    return assembler_;
+  }
+
  private:
   Assembler* assembler_;
   PositionState state_;
 #ifdef ENABLE_GDB_JIT_INTERFACE
   GDBJITLineInfo* gdbjit_lineinfo_;
 #endif
-
+  // Currently jit_handler_data_ is used to store JITHandler-specific data
+  // over the lifetime of a PositionsRecorder
+  void* jit_handler_data_;
   friend class PreservePositionScope;
 
   DISALLOW_COPY_AND_ASSIGN(PositionsRecorder);