JS: Factor out Unit type

javascript/ql/src/semmle/javascript/Unit.qll

@@ -0,0 +1,10 @@
+/** Provides the `Unit` class. */
+
+/** The unit type. */
+private newtype TUnit = TMkUnit()
+
+/** The trivial type with a single element. */
+class Unit extends TUnit {
+  /** Gets a textual representation of this element. */
+  string toString() { result = "Unit" }
+}

javascript/ql/src/semmle/javascript/dataflow/Configuration.qll

@@ -72,7 +72,7 @@ private import javascript
 private import internal.FlowSteps
 private import internal.AccessPaths
 private import internal.CallGraphs
-private import internal.Unit
+private import semmle.javascript.Unit
 private import semmle.javascript.internal.CachedStages
 
 /**

javascript/ql/src/semmle/javascript/dataflow/TaintTracking.qll

@@ -15,7 +15,7 @@
 
 import javascript
 private import semmle.javascript.dataflow.internal.FlowSteps as FlowSteps
-private import semmle.javascript.dataflow.internal.Unit
+private import semmle.javascript.Unit
 private import semmle.javascript.dataflow.InferredTypes
 private import semmle.javascript.internal.CachedStages
 

javascript/ql/src/semmle/javascript/dataflow/internal/PreCallGraphStep.qll

@@ -4,14 +4,9 @@
  */
 
 private import javascript
+private import semmle.javascript.Unit
 private import semmle.javascript.internal.CachedStages
 
-private newtype TUnit = MkUnit()
-
-private class Unit extends TUnit {
-  string toString() { result = "unit" }
-}
-
 /**
  * Internal extension point for adding flow edges prior to call graph construction
  * and type tracking.

javascript/ql/src/semmle/javascript/dataflow/internal/Unit.qll

@@ -1,9 +0,0 @@
-private newtype TUnit = MkUnit()
-
-/**
- * A class with only one instance.
- */
-class Unit extends TUnit {
-  /** Gets a textual representation of this element. */
-  final string toString() { result = "Unit" }
-}