Debugger: require debugger to be active when dealing with breaks.

test/mjsunit/regress/regress-prepare-break-while-recompile.js

Index: test/mjsunit/regress/regress-prepare-break-while-recompile.js
diff --git a/test/mjsunit/regress/regress-prepare-break-while-recompile.js b/test/mjsunit/regress/regress-prepare-break-while-recompile.js
index 0aedcab015426fb51d39a4f9e6f59bc9dcc5a93d..0673220e4a9059ec47529250cc8051f29efbd8d5 100644
--- a/test/mjsunit/regress/regress-prepare-break-while-recompile.js
+++ b/test/mjsunit/regress/regress-prepare-break-while-recompile.js
@@ -54,8 +54,10 @@ foo();
 // and (shared) unoptimized code on foo, and sets both to lazy-compile builtin.
 // Clear the break point immediately after to deactivate the debugger.
 // Do all of this after compile graph has been created.
+Debug.setListener(function(){});
 Debug.setBreakPoint(bar, 0, 0);
 Debug.clearAllBreakPoints();
+Debug.setListener(null);
 
 // At this point, concurrent recompilation is still blocked.
 assertUnoptimized(foo, "no sync");