X87: [runtime] Drop redundant %CharFromCode runtime entry.

  port 2b4cb2a1 (r31873)

  original commit message:
  The %StringCharFromCode and %CharFromCode runtime function perform
  exactly the same task, so we need only one of them.

BUG=

Review URL: https://codereview.chromium.org/1432063002

Cr-Commit-Position: refs/heads/master@{#31909}

src/crankshaft/x87/lithium-codegen-x87.cc

@@ -4855,7 +4855,8 @@ void LCodeGen::DoDeferredStringCharFromCode(LStringCharFromCode* instr) {
   PushSafepointRegistersScope scope(this);
   __ SmiTag(char_code);
   __ push(char_code);
-  CallRuntimeFromDeferred(Runtime::kCharFromCode, 1, instr, instr->context());
+  CallRuntimeFromDeferred(Runtime::kStringCharFromCode, 1, instr,
+                          instr->context());
   __ StoreToSafepointRegisterSlot(result, eax);
 }
 

src/x87/code-stubs-x87.cc

@@ -2467,7 +2467,7 @@ void StringCharFromCodeGenerator::GenerateSlow(
   __ bind(&slow_case_);
   call_helper.BeforeCall(masm);
   __ push(code_);
-  __ CallRuntime(Runtime::kCharFromCode, 1);
+  __ CallRuntime(Runtime::kStringCharFromCode, 1);
   if (!result_.is(eax)) {
     __ mov(result_, eax);
   }