Insert debug step check at the beginning of a function.

runtime/vm/debugger_api_impl_test.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "include/dart_mirrors_api.h"
 #include "include/dart_tools_api.h"
 #include "platform/assert.h"
 #include "vm/dart_api_impl.h"
 #include "vm/lockers.h"
 #include "vm/unit_test.h"
@@ skipping 640 matching lines @@
   breakpoint_hit_counter = 0;
   Dart_Handle retval = Invoke("main");
   EXPECT_VALID(retval);
   EXPECT(Dart_IsInteger(retval));
   int64_t int_value = ToInt64(retval);
   EXPECT_EQ(2, int_value);
   EXPECT(breakpoint_hit == true);
 }
 
 static const char* step_into_expected_bpts[] = {
-    "main",
-      "foo",
-        "f1",
-      "foo",
-      "foo",
-        "X.kvmk",
-          "f2",
-        "X.kvmk",
-        "X.kvmk",
-      "foo",
-    "main"
+    "main",        // entry
+    "main",        // call foo
+      "foo",       // entry
+      "foo",       // call f1
+        "f1",      // entry
+      "foo",       // call initializer
+      "foo",       // call kvmk
+        "X.kvmk",  // entry
+        "X.kvmk",  // call
+          "f2",    // entry
+          "f2",    // return
+        "X.kvmk",  // call +
+        "X.kvmk",  // return
+      "foo",       // return
+    "main"         // return
 };
 
 void TestStepIntoHandler(Dart_IsolateId isolate_id,
                          intptr_t bp_id,
                          const Dart_CodeLocation& location) {
   Dart_StackTrace trace;
   Dart_GetStackTrace(&trace);
   const intptr_t expected_bpts_length = ARRAY_SIZE(step_into_expected_bpts);
   intptr_t trace_len;
   Dart_Handle res = Dart_StackTraceLength(trace, &trace_len);
@@ skipping 1627 matching lines @@
       " null, 3, 7, 1, 8, 6, 9, 10, 10, 11, 11, 13,"
       " null, 4, 13, 3, 14, 10,"
       " null, 5, 17, 5, 18, 9, 19, 12,"
       " null, 6, 21, 1,"
       " null, 8, 24, 1, 25, 5, 26, 6, 27, 8,"
       " null, 9, 29, 1]",
       tokens_cstr);
 }
 
 }  // namespace dart