Get rid of duplicated CPU::DebugBreak() method.

src/x64/cpu-x64.cc

Index: src/x64/cpu-x64.cc
diff --git a/src/x64/cpu-x64.cc b/src/x64/cpu-x64.cc
index 96c5330832689c50a74255088f4dd056b8623b77..4fa290a8b5ff19380b69ea23c759b20e7582efbf 100644
--- a/src/x64/cpu-x64.cc
+++ b/src/x64/cpu-x64.cc
@@ -72,18 +72,6 @@ void CPU::FlushICache(void* start, size_t size) {
 #endif
 }
 
-
-void CPU::DebugBreak() {
-#ifdef _MSC_VER
-  // To avoid Visual Studio runtime support the following code can be used
-  // instead
-  // __asm { int 3 }
-  __debugbreak();
-#else
-  asm("int $3");
-#endif
-}
-
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64