[wasm] Provide better stack traces for asm.js code

src/wasm/wasm-debug.h

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_WASM_DEBUG_H_
 #define V8_WASM_DEBUG_H_
 
 #include "src/handles.h"
 #include "src/objects.h"
 
@@ skipping 19 matching lines @@
   // Disassemble the specified function from this module.
   static Handle<String> DisassembleFunction(Handle<WasmDebugInfo> debug_info,
                                             int func_index);
 
   // Get the offset table for the specified function, mapping from byte offsets
   // to position in the disassembly.
   // Returns an array with three entries per instruction: byte offset, line and
   // column.
   static Handle<FixedArray> GetFunctionOffsetTable(
       Handle<WasmDebugInfo> debug_info, int func_index);
+
+  // Get the asm.js source position from a byte offset.
+  // Must only be called if the associated wasm object was created from asm.js.
+  static int GetAsmJsSourcePosition(Handle<WasmDebugInfo> debug_info,
+                                    int func_index, int byte_offset);
 };
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_DEBUG_H_