X87: Reland "Initial switch to Chromium-style CHECK_* and DCHECK_* macros

port c65ae4f1 (r26346).

   fix one spelling error introduced by this CL.

original commit message:
  Reland "Initial switch to Chromium-style CHECK_* and DCHECK_* macros.".

BUG=

Review URL: https://codereview.chromium.org/886833006

Cr-Commit-Position: refs/heads/master@{#26507}

src/x87/full-codegen-x87.cc

@@ -3702,7 +3702,7 @@ void FullCodeGenerator::EmitValueOf(CallRuntime* expr) {
 void FullCodeGenerator::EmitDateField(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   DCHECK(args->length() == 2);
-  DCHECK_NOT_NUL(args->at(1)->AsLiteral());
+  DCHECK_NOT_NULL(args->at(1)->AsLiteral());
   Smi* index = Smi::cast(*(args->at(1)->AsLiteral()->value()));
 
   VisitForAccumulatorValue(args->at(0));  // Load the object.