JS: Include content properties in type-tracker properties

Reminder: we have two PropertyName classes because the one in Contents.qll can't depend on DataFlow::Node.

Author: asgerf

javascript/ql/lib/semmle/javascript/dataflow/internal/StepSummary.qll

@@ -1,6 +1,7 @@
 import javascript
 private import semmle.javascript.dataflow.TypeTracking
 private import semmle.javascript.internal.CachedStages
+private import semmle.javascript.dataflow.internal.Contents as Contents
 private import sharedlib.SummaryTypeTracker as SummaryTypeTracker
 private import FlowSteps
 
@@ -30,6 +31,8 @@ private module Cached {
         SharedTypeTrackingStep::loadStoreStep(_, _, _, this)
         or
         this = DataFlow::PseudoProperties::arrayLikeElement()
+        or
+        this instanceof Contents::Private::PropertyName
       }
     }
 

javascript/ql/test/library-tests/TypeTracking2/summaries.js

@@ -48,7 +48,7 @@ function m5() {
   // Store and read to a property that isn't mentioned anywhere in the source code.
   const store = mkSummary("Argument[0]", "ReturnValue.Member[propOnlyMentionedInSummary]");
   const read = mkSummary("Argument[0].Member[propOnlyMentionedInSummary]", "ReturnValue");
-  sink(read(store(source("m5.1")))); // $ MISSING: track=m5.1
+  sink(read(store(source("m5.1")))); // $ track=m5.1
   sink(read(source("m5.1")));
   sink(store(source("m5.1")));
   sink(store(read(source("m5.1"))));