[wasm] Add inspector test for stepping

src/runtime/runtime-debug.cc

 // Copyright 2014 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.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/compiler.h"
 #include "src/debug/debug-evaluate.h"
 #include "src/debug/debug-frames.h"
@@ skipping 1648 matching lines @@
                         sourceText, NONE);
 
   return jsinfo;
 }
 
 namespace {
 
 int ScriptLinePositionWithOffset(Handle<Script> script, int line, int offset) {
   if (line < 0 || offset < 0) return -1;
 
-  if (line == 0) return ScriptLinePosition(script, line) + offset;
+  if (line == 0 || offset == 0)
+    return ScriptLinePosition(script, line) + offset;
 
   Script::PositionInfo info;
   if (!Script::GetPositionInfo(script, offset, &info, Script::NO_OFFSET)) {
     return -1;
   }
 
   const int total_line = info.line + line;
   return ScriptLinePosition(script, total_line);
 }
 
@@ skipping 250 matching lines @@
 }
 
 
 RUNTIME_FUNCTION(Runtime_DebugBreakInOptimizedCode) {
   UNIMPLEMENTED();
   return NULL;
 }
 
 }  // namespace internal
 }  // namespace v8