Turn on crankshaft as the default for X64 and ARM

Review URL: http://codereview.chromium.org/6603012

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7035 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/flag-definitions.h

@@ -97,11 +97,7 @@ private:
 #define FLAG FLAG_FULL
 
 // Flags for Crankshaft.
-#ifdef V8_TARGET_ARCH_IA32
 DEFINE_bool(crankshaft, true, "use crankshaft")
-#else
-DEFINE_bool(crankshaft, false, "use crankshaft")
-#endif
 DEFINE_string(hydrogen_filter, "", "hydrogen use/trace filter")
 DEFINE_bool(use_hydrogen, true, "use generated hydrogen for compilation")
 DEFINE_bool(build_lithium, true, "use lithium chunk builder")