Change the order of arguments of the (One|Two)ByteSeqStringSetChar intrinsic.

src/string.js

Index: src/string.js
diff --git a/src/string.js b/src/string.js
index ae65264d4a3ae2c29cc39add829dd45e51ccf0c3..99f5fc976c2996506fcc2504c377fdedb28b6839 100644
--- a/src/string.js
+++ b/src/string.js
@@ -812,7 +812,7 @@ function StringFromCharCode(code) {
     if (!%_IsSmi(code)) code = ToNumber(code) & 0xffff;
     if (code < 0) code = code & 0xffff;
     if (code > 0xff) break;
-    %_OneByteSeqStringSetChar(one_byte, i, code);
+    %_OneByteSeqStringSetChar(i, code, one_byte);
   }
   if (i == n) return one_byte;
   one_byte = %TruncateString(one_byte, i);
@@ -821,7 +821,7 @@ function StringFromCharCode(code) {
   for (var j = 0; i < n; i++, j++) {
     var code = %_Arguments(i);
     if (!%_IsSmi(code)) code = ToNumber(code) & 0xffff;
-    %_TwoByteSeqStringSetChar(two_byte, j, code);
+    %_TwoByteSeqStringSetChar(j, code, two_byte);
   }
   return one_byte + two_byte;
 }