Implement own value getter from hashtable ast

Ideally we should use HashtableAst.SafeGetValue() but that API is available only on PSv4 and onwards. As we support PSv3, we need our own implementation. And since we do not want any discrepancy in behavior across different PS versions, we use this custom implementation for all PS versions.

Author: Kapil Borle

Engine/Generic/Settings.cs

@@ -310,7 +310,9 @@ private void parseSettingsFile(string settingsFilePath)
             Hashtable hashtable;
             try
             {
-                hashtable = hashTableAst.SafeGetValue() as Hashtable;
+                // ideally we should use HashtableAst.SafeGetValue() but since
+                // it is not available on PSv3, we resort to our own narrow implementation.
+                hashtable = GetHashtableFromHashTableAst(hashTableAst);
             }
             catch (InvalidOperationException e)
             {
@@ -325,15 +327,6 @@ private void parseSettingsFile(string settingsFilePath)
             parseSettingsHashtable(hashtable);
         }
 
-        private Hashtable GetValue(HashtableAst hashtableAst)
-        {
-#if !PSV3
-            return hashtableAst.SafeGetValue() as Hashtable;
-#else
-            return GetHashtableFromHashTableAst(hashTableAst);
-#endif
-        }
-
         private Hashtable GetHashtableFromHashTableAst(HashtableAst hashTableAst)
         {
             var output = new Hashtable();