Bigger stepping granularity in debugging

runtime/vm/debugger.h

Index: runtime/vm/debugger.h
===================================================================
--- runtime/vm/debugger.h	(revision 8117)
+++ runtime/vm/debugger.h	(working copy)
@@ -266,7 +266,7 @@
   SourceBreakpoint* SetBreakpoint(const Function& target_function,
                                   intptr_t token_index);
   void RemoveInternalBreakpoints();
-  void RemoveCodeBreakpoints(SourceBreakpoint* src_bpt);
+  void UnlinkCodeBreakpoints(SourceBreakpoint* src_bpt);
   void RegisterSourceBreakpoint(SourceBreakpoint* bpt);
   void RegisterCodeBreakpoint(CodeBreakpoint* bpt);
   SourceBreakpoint* GetSourceBreakpoint(const Function& func,
@@ -281,6 +281,8 @@
 
   void SignalBpResolved(SourceBreakpoint *bpt);
 
+  bool IsDebuggable(const Function& func);
+
   intptr_t nextId() { return next_id_++; }
 
   Isolate* isolate_;
@@ -302,6 +304,10 @@
   // Tells debugger what to do when resuming execution after a breakpoint.
   ResumeAction resume_action_;
 
+  // If >= 0, last_bpt_line contains the line number of the last breakpoint
+  // location for which the breakpoint callback function was called.
+  intptr_t last_bpt_line_;
+
   // Do not call back to breakpoint handler if this flag is set.
   // Effectively this means ignoring breakpoints. Set when Dart code may
   // be run as a side effect of getting values of fields.