Clarify the order of frame summaries and rename getters

src/frames.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_FRAMES_H_
 #define V8_FRAMES_H_
 
 #include "src/allocation.h"
 #include "src/handles.h"
 #include "src/safepoint-table.h"
@@ skipping 840 matching lines @@
   };
 
 #undef FRAME_SUMMARY_FIELD
 #define FRAME_SUMMARY_CONS(kind, type, field, desc) \
   FrameSummary(type summ) : field(summ) {}  // NOLINT
   FRAME_SUMMARY_VARIANTS(FRAME_SUMMARY_CONS)
 #undef FRAME_SUMMARY_CONS
 
   ~FrameSummary();
 
-  static inline FrameSummary GetFirst(const StandardFrame* frame) {
-    return Get(frame, 0);
-  }
+  static FrameSummary GetTop(const StandardFrame* frame);
+  static FrameSummary GetBottom(const StandardFrame* frame);
+  static FrameSummary GetSingle(const StandardFrame* frame);
   static FrameSummary Get(const StandardFrame* frame, int index);
-  static FrameSummary GetSingle(const StandardFrame* frame);
 
   // Dispatched accessors.
   Handle<Object> receiver() const;
   int code_offset() const;
   bool is_constructor() const;
   bool is_subject_to_debugging() const;
   Handle<Object> script() const;
   int SourcePosition() const;
   int SourceStatementPosition() const;
   Handle<String> FunctionName() const;
@@ skipping 41 matching lines @@
   // Access the parameters.
   virtual Object* GetParameter(int index) const;
   virtual int ComputeParametersCount() const;
 
   void SetCallerFp(Address caller_fp) override;
 
   // Check if this frame is a constructor frame invoked through 'new'.
   virtual bool IsConstructor() const;
 
   // Build a list with summaries for this frame including all inlined frames.
+  // The functions are ordered bottom-to-top (i.e. summaries.last() is the
+  // top-most activation; caller comes before callee).
   virtual void Summarize(
       List<FrameSummary>* frames,
       FrameSummary::Mode mode = FrameSummary::kExactSummary) const;
 
   static StandardFrame* cast(StackFrame* frame) {
     DCHECK(frame->is_standard());
     return static_cast<StandardFrame*>(frame);
   }
 
  protected:
@@ skipping 611 matching lines @@
 
 
 // Reads all frames on the current stack and copies them into the current
 // zone memory.
 Vector<StackFrame*> CreateStackMap(Isolate* isolate, Zone* zone);
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_FRAMES_H_