Revert "Use implicit null checks inside try blocks."

Fails gcstress tests.

This reverts commit 7aa7560683626c7893011271c241b3265ded1dc3.

Change-Id: I4f5c89048b9ffddbafa02f3001e329ff87058ca2
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index bf96be2..4689ccb 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -4979,10 +4979,16 @@
 }
 
 void LocationsBuilderX86::VisitNullCheck(HNullCheck* instruction) {
-  LocationSummary* locations = codegen_->CreateNullCheckLocations(instruction);
-  if (!codegen_->GetCompilerOptions().GetImplicitNullChecks()) {
-    // Explicit null checks can use any location.
-    locations->SetInAt(0, Location::Any());
+  LocationSummary::CallKind call_kind = instruction->CanThrowIntoCatchBlock()
+      ? LocationSummary::kCallOnSlowPath
+      : LocationSummary::kNoCall;
+  LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
+  Location loc = codegen_->IsImplicitNullCheckAllowed(instruction)
+      ? Location::RequiresRegister()
+      : Location::Any();
+  locations->SetInAt(0, loc);
+  if (instruction->HasUses()) {
+    locations->SetOut(Location::SameAsFirstInput());
   }
 }