Added native to split OneByteString with a char code as pattern.

runtime/lib/string.cc

Index: runtime/lib/string.cc
===================================================================
--- runtime/lib/string.cc	(revision 15607)
+++ runtime/lib/string.cc	(working copy)
@@ -74,6 +74,30 @@
 }
 
 
+DEFINE_NATIVE_ENTRY(OneByteString_splitWithCharCode, 2) {
+  const String& receiver = String::CheckedHandle(arguments->NativeArgAt(0));
+  ASSERT(receiver.IsOneByteString());
+  GET_NATIVE_ARGUMENT(Smi, smi_split_code, arguments->NativeArgAt(1));
+  const intptr_t len = receiver.Length();
+  const intptr_t split_code = smi_split_code.Value();
+  const GrowableObjectArray& result = GrowableObjectArray::Handle(
+      GrowableObjectArray::New(4, Heap::kNew));
+  String& str = String::Handle();
+  intptr_t start = 0;
+  intptr_t i = 0;
+  for (; i < len; i++) {
+    if (split_code == receiver.CharAt(i)) {
+      str = String::SubString(receiver, start, (i - start));
+      result.Add(str);
+      start = i + 1;
+    }
+  }
+  str = String::SubString(receiver, start, (i - start));
+  result.Add(str);
+  return result.raw();
+}
+
+
 DEFINE_NATIVE_ENTRY(String_getHashCode, 1) {
   const String& receiver = String::CheckedHandle(arguments->NativeArgAt(0));
   intptr_t hash_val = receiver.Hash();