Update V8 to r4924 as required by WebKit r61871

Change-Id: Ic819dad0c1c9e035b8ffd306c96656ba87c5e85a
diff --git a/src/debug-debugger.js b/src/debug-debugger.js
index 77fa1dd..d5e91cb 100644
--- a/src/debug-debugger.js
+++ b/src/debug-debugger.js
@@ -295,7 +295,6 @@
 }
 
 
-
 ScriptBreakPoint.prototype.hit_count = function() {
   return this.hit_count_;
 };
@@ -389,7 +388,10 @@
   // Create a break point object and set the break point.
   break_point = MakeBreakPoint(pos, this.line(), this.column(), this);
   break_point.setIgnoreCount(this.ignoreCount());
-  %SetScriptBreakPoint(script, pos, break_point);
+  pos = %SetScriptBreakPoint(script, pos, break_point);
+  if (!IS_UNDEFINED(pos)) {
+    this.actual_location = script.locationFromPosition(pos);
+  }
 
   return break_point;
 };