MIPS[64]: Fix `[builtins]: Uniformly push argument count in TF-generated builtins`

Fix 4447405b

A typo in the patch caused failures on MIPS64. There were no failures on MIPS32,
but I guess the same patch needs to be applied there as well.

BUG=

Review-Url: https://codereview.chromium.org/2473343002
Cr-Commit-Position: refs/heads/master@{#40763}

src/compiler/mips/code-generator-mips.cc

@@ -1930,7 +1930,8 @@ void CodeGenerator::AssembleConstructFrame() {
     }
   }
 
-  int shrink_slots = frame()->GetSpillSlotCount();
+  int shrink_slots =
+      frame()->GetTotalFrameSlotCount() - descriptor->CalculateFixedFrameSize();
 
   if (info()->is_osr()) {
     // TurboFan OSR-compiled functions cannot be entered directly.

src/compiler/mips64/code-generator-mips64.cc

@@ -2239,6 +2239,9 @@ void CodeGenerator::AssembleConstructFrame() {
       __ mov(fp, sp);
     } else if (descriptor->IsJSFunctionCall()) {
       __ Prologue(this->info()->GeneratePreagedPrologue());
+      if (descriptor->PushArgumentCount()) {
+        __ Push(kJavaScriptCallArgCountRegister);
+      }
     } else {
       __ StubPrologue(info()->GetOutputStackFrameType());
     }