Fix presumbit errors in previous commit

TBR=kasperl@chromium.org
Review URL: http://codereview.chromium.org/3249001

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5360 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/debug.h

@@ -952,7 +952,7 @@ class DisableBreak BASE_EMBEDDED {
 // code.
 class Debug_Address {
  public:
-  Debug_Address(Debug::AddressId id) : id_(id) { }
+  explicit Debug_Address(Debug::AddressId id) : id_(id) { }
 
   static Debug_Address AfterBreakTarget() {
     return Debug_Address(Debug::k_after_break_target_address);