[debugger] use absolute source positions for break locations.

test/cctest/heap/test-heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1521 matching lines @@
     function->shared()->code()->MakeOlder(static_cast<MarkingParity>(i % 2));
   }
 
   // Simulate incremental marking so that the function is enqueued as
   // code flushing candidate.
   heap::SimulateIncrementalMarking(heap);
 
   // Enable the debugger and add a breakpoint while incremental marking
   // is running so that incremental marking aborts and code flushing is
   // disabled.
-  int position = 0;
+  int position = function->shared()->start_position();
   Handle<Object> breakpoint_object(Smi::FromInt(0), isolate);
   EnableDebugger(CcTest::isolate());
   isolate->debug()->SetBreakPoint(function, breakpoint_object, &position);
   isolate->debug()->ClearAllBreakPoints();
   DisableDebugger(CcTest::isolate());
 
   // Force optimization now that code flushing is disabled.
   { v8::HandleScope scope(CcTest::isolate());
     CompileRun("%OptimizeFunctionOnNextCall(foo); foo();");
   }
@@ skipping 5332 matching lines @@
       chunk, chunk->area_end() - kPointerSize, chunk->area_end());
   slots[chunk->area_end() - kPointerSize] = false;
   RememberedSet<OLD_TO_NEW>::Iterate(chunk, [&slots](Address addr) {
     CHECK(slots[addr]);
     return KEEP_SLOT;
   });
 }
 
 }  // namespace internal
 }  // namespace v8