[interpreter, debugger] abstraction for source position calculation.

src/runtime/runtime-function.cc

Index: src/runtime/runtime-function.cc
diff --git a/src/runtime/runtime-function.cc b/src/runtime/runtime-function.cc
index befd3370984b7b753c21f6bb6c19c3b58b63d4b0..88f6f3b1695edbaaf88d080c06ae8c07c3b6ab6d 100644
--- a/src/runtime/runtime-function.cc
+++ b/src/runtime/runtime-function.cc
@@ -86,13 +86,9 @@ RUNTIME_FUNCTION(Runtime_FunctionGetPositionForOffset) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 2);
 
-  CONVERT_ARG_CHECKED(Code, code, 0);
+  CONVERT_ARG_CHECKED(AbstractCode, abstract_code, 0);
   CONVERT_NUMBER_CHECKED(int, offset, Int32, args[1]);
-
-  RUNTIME_ASSERT(0 <= offset && offset < code->Size());
-
-  Address pc = code->address() + offset;
-  return Smi::FromInt(code->SourcePosition(pc));
+  return Smi::FromInt(abstract_code->SourcePosition(offset));
 }