[debugger] add precise mode for code coverage.

src/feedback-vector-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_FEEDBACK_VECTOR_INL_H_
 #define V8_FEEDBACK_VECTOR_INL_H_
 
 #include "src/factory.h"
 #include "src/feedback-vector.h"
 #include "src/globals.h"
@@ skipping 78 matching lines @@
 }
 
 SharedFunctionInfo* FeedbackVector::shared_function_info() const {
   return SharedFunctionInfo::cast(get(kSharedFunctionInfoIndex));
 }
 
 int FeedbackVector::invocation_count() const {
   return Smi::cast(get(kInvocationCountIndex))->value();
 }
 
+void FeedbackVector::clear_invocation_count() {
+  set(kInvocationCountIndex, Smi::kZero);
+}
+
 // Conversion from an integer index to either a slot or an ic slot.
 // static
 FeedbackSlot FeedbackVector::ToSlot(int index) {
   DCHECK_GE(index, kReservedIndexCount);
   return FeedbackSlot(index - kReservedIndexCount);
 }
 
 Object* FeedbackVector::Get(FeedbackSlot slot) const {
   return get(GetIndex(slot));
 }
@@ skipping 189 matching lines @@
 #endif
   int index = vector()->GetIndex(slot()) + 1;
   vector()->set(index, feedback_extra, mode);
 }
 
 Isolate* FeedbackNexus::GetIsolate() const { return vector()->GetIsolate(); }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_FEEDBACK_VECTOR_INL_H_