[debugger] use absolute source positions for break locations.

test/cctest/heap/test-heap.cc

Index: test/cctest/heap/test-heap.cc
diff --git a/test/cctest/heap/test-heap.cc b/test/cctest/heap/test-heap.cc
index 7dab3ffc42b6f2e22d814aa3e075bcbf034fe7a2..aa2b704ca7c2d04ee2bf0c6210bbfea97513ab83 100644
--- a/test/cctest/heap/test-heap.cc
+++ b/test/cctest/heap/test-heap.cc
@@ -1539,7 +1539,7 @@ TEST(TestCodeFlushingIncrementalAbort) {
   // 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);