Revert of [builtins] migrate C++ String Iterator builtins to baseline TurboFan

src/code-stub-assembler.cc

Index: src/code-stub-assembler.cc
diff --git a/src/code-stub-assembler.cc b/src/code-stub-assembler.cc
index b1c98904bb01ce300cb3b3bdea192231a558ba38..386cb665f19a0ded59fa64ede49ff5341dd8b134 100644
--- a/src/code-stub-assembler.cc
+++ b/src/code-stub-assembler.cc
@@ -2429,58 +2429,6 @@
   return var_result.value();
 }
 
-Node* CodeStubAssembler::StringFromCodePoint(compiler::Node* codepoint,
-                                             UnicodeEncoding encoding) {
-  Variable var_result(this, MachineRepresentation::kTagged);
-  var_result.Bind(EmptyStringConstant());
-
-  Label if_isword16(this), if_isword32(this), return_result(this);
-
-  Branch(Uint32LessThan(codepoint, Int32Constant(0x10000)), &if_isword16,
-         &if_isword32);
-
-  Bind(&if_isword16);
-  {
-    var_result.Bind(StringFromCharCode(codepoint));
-    Goto(&return_result);
-  }
-
-  Bind(&if_isword32);
-  {
-    switch (encoding) {
-      case UnicodeEncoding::UTF16:
-        break;
-      case UnicodeEncoding::UTF32: {
-        // Convert UTF32 to UTF16 code units, and store as a 32 bit word.
-        Node* lead_offset = Int32Constant(0xD800 - (0x10000 >> 10));
-
-        // lead = (codepoint >> 10) + LEAD_OFFSET
-        Node* lead =
-            Int32Add(WordShr(codepoint, Int32Constant(10)), lead_offset);
-
-        // trail = (codepoint & 0x3FF) + 0xDC00;
-        Node* trail = Int32Add(Word32And(codepoint, Int32Constant(0x3FF)),
-                               Int32Constant(0xDC00));
-
-        // codpoint = (trail << 16) | lead;
-        codepoint = Word32Or(WordShl(trail, Int32Constant(16)), lead);
-        break;
-      }
-    }
-
-    Node* value = AllocateSeqTwoByteString(2);
-    StoreNoWriteBarrier(
-        MachineRepresentation::kWord32, value,
-        IntPtrConstant(SeqTwoByteString::kHeaderSize - kHeapObjectTag),
-        codepoint);
-    var_result.Bind(value);
-    Goto(&return_result);
-  }
-
-  Bind(&return_result);
-  return var_result.value();
-}
-
 Node* CodeStubAssembler::StringToNumber(Node* context, Node* input) {
   Label runtime(this, Label::kDeferred);
   Label end(this);