[analyzer] Nullability: Don't infer nullable when passing as nullable parameter.

You can't really infer anything from that.

clang/lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp

@@ -728,11 +728,6 @@ void NullabilityChecker::checkPreCall(const CallEvent &Call,
       }
       continue;
     }
-    // No tracked nullability yet.
-    if (ArgExprTypeLevelNullability != Nullability::Nullable)
-      continue;
-    State = State->set<NullabilityMap>(
-        Region, NullabilityState(ArgExprTypeLevelNullability, ArgExpr));
   }
   if (State != OrigState)
     C.addTransition(State);

clang/test/Analysis/nullability.m

@@ -0,0 +1,12 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker core,nullability -w -verify %s
+
+// expected-no-diagnostics
+
+id _Nonnull conjure_nonnull();
+void use_nullable(_Nullable id x);
+
+id _Nonnull foo() {
+  void *j = conjure_nonnull();
+  use_nullable(j);
+  return j; // no-warning
+}