Revert of [inspector] migrate stepping related methods to debug-interface

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 4614f28ef9582b5fb85236342d98d014b135626b..3a6ff94a9c34330ce8eb4cdadc55f96a0db69109 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -8811,24 +8811,6 @@
                                                     type != NoBreakOnException);
 }
 
-void DebugInterface::PrepareStep(Isolate* v8_isolate, StepAction action) {
-  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
-  ENTER_V8(isolate);
-  CHECK(isolate->debug()->CheckExecutionState());
-  // Clear all current stepping setup.
-  isolate->debug()->ClearStepping();
-  // Prepare step.
-  isolate->debug()->PrepareStep(static_cast<i::StepAction>(action));
-}
-
-void DebugInterface::ClearStepping(Isolate* v8_isolate) {
-  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(v8_isolate);
-  ENTER_V8(isolate);
-  CHECK(isolate->debug()->CheckExecutionState());
-  // Clear all current stepping setup.
-  isolate->debug()->ClearStepping();
-}
-
 Local<String> CpuProfileNode::GetFunctionName() const {
   const i::ProfileNode* node = reinterpret_cast<const i::ProfileNode*>(this);
   i::Isolate* isolate = node->isolate();