[V8] Fixed infinite loop in Debug::PrepareStep

test/cctest/test-debug.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 3807 matching lines @@
   foo->Call(env->Global(), 0, NULL);
 
   // Without stepping only the debugger statement is hit.
   CHECK_EQ(1, break_point_hit_count);
 
   v8::Debug::SetDebugEventListener(NULL);
   CheckDebuggerUnloaded();
 }
 
 
+// Test that step in works with Function.call.apply.
+TEST(DebugStepFunctionCallApply) {
+  DebugLocalContext env;
+  v8::Isolate* isolate = env->GetIsolate();
+  v8::HandleScope scope(isolate);
+
+  // Create a function for testing stepping.
+  v8::Local<v8::Function> foo =
+      CompileFunction(&env,
+                      "function bar() { }"
+                      "function foo(){ debugger;"
+                      "                Function.call.apply(bar);"

[yurys, 2015/06/16 10:37:15]

Can you add one more test for a deeper case, something like

Function.call.apply(Function.call, [Function.call, bar])?

[kozy, 2015/06/16 10:49:58]

Done.

+                      "}",
+                      "foo");
+
+  // Register a debug event listener which steps and counts.
+  v8::Debug::SetDebugEventListener(DebugEventStep);
+  step_action = StepIn;
+
+  // Check stepping where the if condition in bar is false.
+  break_point_hit_count = 0;
+  foo->Call(env->Global(), 0, NULL);
+  CHECK_EQ(4, break_point_hit_count);
+
+  v8::Debug::SetDebugEventListener(NULL);
+  CheckDebuggerUnloaded();
+
+  // Register a debug event listener which just counts.
+  v8::Debug::SetDebugEventListener(DebugEventBreakPointHitCount);
+
+  break_point_hit_count = 0;
+  foo->Call(env->Global(), 0, NULL);
+
+  // Without stepping only the debugger statement is hit.
+  CHECK_EQ(1, break_point_hit_count);
+
+  v8::Debug::SetDebugEventListener(NULL);
+  CheckDebuggerUnloaded();
+}
+
+
 // Tests that breakpoint will be hit if it's set in script.
 TEST(PauseInScript) {
   DebugLocalContext env;
   v8::HandleScope scope(env->GetIsolate());
   env.ExposeDebug();
 
   // Register a debug event listener which counts.
   v8::Debug::SetDebugEventListener(DebugEventCounter);
 
   // Create a script that returns a function.
@@ skipping 3809 matching lines @@
       "let y = 2;               \n"
       "debugger;                \n"
       "x * y",
       30);
   ExpectInt32(
       "x = 1; y = 2; \n"
       "debugger;"
       "x * y",
       30);
 }