Update V8 to r6101 as required by WebKit r74534

Change-Id: I7f84af8dd732f11898fd644b2c2b1538914cb78d
diff --git a/test/mjsunit/debug-clearbreakpointgroup.js b/test/mjsunit/debug-clearbreakpointgroup.js
index e6677f9..0cfc5c9 100644
--- a/test/mjsunit/debug-clearbreakpointgroup.js
+++ b/test/mjsunit/debug-clearbreakpointgroup.js
@@ -115,3 +115,8 @@
 assertEquals([bp2, bp3, bp5].sort(), breakpointNumbers.sort());
 
 assertFalse(exception, "exception in listener");
+
+// Clear all breakpoints to allow the test to run again (--stress-opt).
+Debug.clearBreakPoint(bp2);
+Debug.clearBreakPoint(bp3);
+Debug.clearBreakPoint(bp5);