[analyzer] Add test case for reference to null pointer param check

This tests that we track the original Expr if getDerefExpr fails.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176754 91177308-0d34-0410-b5e6-96231b3b80d8
[analyzer] Rename AttrNonNullChecker -> NonNullParamChecker

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176755 91177308-0d34-0410-b5e6-96231b3b80d8
[analyzer] Make Suppress IDC checker aware that it might not start from the same node it was registered at

The visitor used to assume that the value it’s tracking is null in the first node it examines. This is not true.
If we are registering the Suppress Inlined Defensive checks visitor while traversing in another visitor
(such as FindlastStoreVisitor). When we restart with the IDC visitor, the invariance of the visitor does
not hold since the symbol we are tracking no longer exists at that point.

I had to pass the ErrorNode when creating the IDC visitor, because, in some cases, node N is
neither the error node nor will be visible along the path (we had not finalized the path at that point
and are dealing with ExplodedGraph.)

We should revisit the other visitors which might not be aware that they might get nodes, which are
later in path than the trigger point.

This suppresses a number of inline defensive checks in JavaScriptCore.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176756 91177308-0d34-0410-b5e6-96231b3b80d8