Track JS allocations as they arrive with no affection on performance when tracking is switched off

test/cctest/test-heap-profiler.cc

Index: test/cctest/test-heap-profiler.cc
diff --git a/test/cctest/test-heap-profiler.cc b/test/cctest/test-heap-profiler.cc
index e30fcc00c9d55e091a86fd50dd89b0001e8ad096..16639be3230095fd168c04141146140b1ef885b4 100644
--- a/test/cctest/test-heap-profiler.cc
+++ b/test/cctest/test-heap-profiler.cc
@@ -1960,3 +1960,19 @@ TEST(JSFunctionHasCodeLink) {
       GetProperty(foo_func, v8::HeapGraphEdge::kInternal, "code");
   CHECK_NE(NULL, code);
 }
+
+
+// This is an example of using checking of JS allocations tracking in a test.
+TEST_TRACK_ALLOCATIONS(HeapObjectsTracker) {
+  v8::HandleScope scope;
+  LocalContext env;
+  CompileRun("var a = 1.2");
+  CompileRun("var a = 1.2; var b = 1.0; var c = 1.0;");
+  CompileRun(
+    "var a = [];"
+    "for (var i = 0; i < 5; ++i)"
+    "    a[i] = i;\n"
+    "for (var i = 0; i < 3; ++i)"
+    "    a.shift();\n"
+    );
+}