[runtime] Implement encodeURI as single runtime function.

src/bignum.cc

Index: src/bignum.cc
diff --git a/src/bignum.cc b/src/bignum.cc
index e7c6747665f12f1e5c6832cf1f54eea271f35d21..e2a9c4e55777abe46b815416dd4082546a5313ca 100644
--- a/src/bignum.cc
+++ b/src/bignum.cc
@@ -539,13 +539,6 @@ static int SizeInHexChars(S number) {
 }
 
 
-static char HexCharOfValue(int value) {
-  DCHECK(0 <= value && value <= 16);
-  if (value < 10) return value + '0';
-  return value - 10 + 'A';
-}
-
-
 bool Bignum::ToHexString(char* buffer, int buffer_size) const {
   DCHECK(IsClamped());
   // Each bigit must be printable as separate hex-character.