JS: Propagate through non-null assertions

Author: asgerf

javascript/ql/lib/semmle/javascript/internal/NameResolution.qll

@@ -128,6 +128,13 @@ module NameResolution {
       node2 = expr
     )
     or
+    exists(NonNullAssertion assertion |
+      // For the time being we don't use this for nullness analysis, so just
+      // propagate through these assertions.
+      node1 = assertion.getExpression() and
+      node2 = assertion
+    )
+    or
     exists(FunctionTypeExpr fun |
       node1 = fun.getFunction() and
       node2 = fun