Fix compile failure with very strict gcc warning rules on Linux.

TBR=kasperl

Review URL: http://codereview.chromium.org/8857

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@631 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/variables.cc

@@ -88,7 +88,7 @@ void UseCount::Print() {
 // Implementation StaticType.
 
 
-char* StaticType::Type2String(StaticType* type) {
+const char* StaticType::Type2String(StaticType* type) {
   switch (type->kind_) {
     case UNKNOWN:
       return "UNKNOWN";

src/variables.h

@@ -83,7 +83,7 @@ class StaticType BASE_EMBEDDED {
     kind_ = other->kind_;
   }
 
-  static char* Type2String(StaticType* type);
+  static const char* Type2String(StaticType* type);
 
   // LIKELY_SMI accessors
   void SetAsLikelySmi() {