debug: cache SharedFunctionInfo for multi-bp set

src/debug-debugger.js

 // 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.
 "use strict";
 
 // Default number of frames to include in the response to backtrace request.
 var kDefaultBacktraceLength = 10;
 
 var Debug = {};
 
@@ skipping 451 matching lines @@
     }
   }
   break_points = remaining_break_points;
   this.break_points_ = [];
 };
 
 
 // Function called from runtime when a new script is compiled to set any script
 // break points set in this script.
 function UpdateScriptBreakPoints(script) {
+  var list = [];
   for (var i = 0; i < script_break_points.length; i++) {
     var break_point = script_break_points[i];
     if ((break_point.type() == Debug.ScriptBreakPointType.ScriptName ||
          break_point.type() == Debug.ScriptBreakPointType.ScriptRegExp) &&
         break_point.matchesScript(script)) {
-      break_point.set(script);
+      list.push(break_point);
     }
   }
+
+  // Cache the shared infos in script to avoid iterating through heap twice
+  if (list.length > 1) {
+    %CollectSharedFunctionInfoInScript(script);
+  }
+
+  for (var i = 0; i < list.length; i++) {
+    list[i].set(script);
+  }
 }
 
 
 function GetScriptBreakPoints(script) {
   var result = [];
   for (var i = 0; i < script_break_points.length; i++) {
     if (script_break_points[i].matchesScript(script)) {
       result.push(script_break_points[i]);
     }
   }
@@ skipping 2070 matching lines @@
     case 'string':
     case 'number':
       json = value;
       break;
 
     default:
       json = null;
   }
   return json;
 }