Add "Version" command

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 9eeffd10c0f1097d60226c3753d402c101fcc422..b557ed5c3b479fecc141e81b0b3b7c445ff3d3c6 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -7659,6 +7659,18 @@ static Object* Runtime_CollectStackTrace(Arguments args) {
 }
 
 
+// Returns V8 version as a string.
+static Object* Runtime_GetV8Version(Arguments args) {
+  ASSERT_EQ(args.length(), 0);
+
+  NoHandleAllocation ha;
+
+  const char* version_string = v8::V8::GetVersion();
+
+  return Heap::AllocateStringFromAscii(CStrVector(version_string), NOT_TENURED);
+}
+
+
 static Object* Runtime_Abort(Arguments args) {
   ASSERT(args.length() == 2);
   OS::PrintError("abort: %s\n", reinterpret_cast<char*>(args[0]) +