jscript: Added jsstr_flatten helper and use it to access string buffer in date.c.

dlls/jscript/date.c

@@ -2054,7 +2054,9 @@ static inline HRESULT date_parse(jsstr_t *input_str, double *ret) {
     DWORD lcid_en;
 
     input_len = jsstr_length(input_str);
-    input = input_str->str;
+    input = jsstr_flatten(input_str);
+    if(!input)
+        return E_OUTOFMEMORY;
 
     for(i=0; i<input_len; i++) {
         if(input[i] == '(') nest_level++;

dlls/jscript/jsstr.h

@@ -53,6 +53,12 @@ static inline jsstr_t *jsstr_addref(jsstr_t *str)
     return str;
 }
 
+/* This will be failable in the future. */
+static inline const WCHAR *jsstr_flatten(jsstr_t *str)
+{
+    return str->str;
+}
+
 static inline BOOL jsstr_eq(jsstr_t *str1, jsstr_t *str2)
 {
     unsigned len = jsstr_length(str1);