Fold ResourceSet::CommonInit into constructor (dotnet/coreclr#23993)

Signed-off-by: dotnet-bot <dotnet-bot@microsoft.com>

Author: jkotas

src/Common/src/CoreLib/System/Resources/ResourceSet.cs

@@ -36,7 +36,7 @@ protected ResourceSet()
         {
             // To not inconvenience people subclassing us, we should allocate a new
             // hashtable here just so that Table is set to something.
-            CommonInit();
+            Table = new Hashtable();
         }
 
         // For RuntimeResourceSet, ignore the Table parameter - it's a wasted 
@@ -50,9 +50,9 @@ internal ResourceSet(bool junk)
         // on disk.
         // 
         public ResourceSet(string fileName)
+            : this()
         {
             Reader = new ResourceReader(fileName);
-            CommonInit();
             ReadResources();
         }
 
@@ -61,26 +61,21 @@ public ResourceSet(string fileName)
         // of data.
         // 
         public ResourceSet(Stream stream)
+            : this()
         {
             Reader = new ResourceReader(stream);
-            CommonInit();
             ReadResources();
         }
 
         public ResourceSet(IResourceReader reader)
+            : this()
         {
             if (reader == null)
                 throw new ArgumentNullException(nameof(reader));
             Reader = reader;
-            CommonInit();
             ReadResources();
         }
 
-        private void CommonInit()
-        {
-            Table = new Hashtable();
-        }
-
         // Closes and releases any resources used by this ResourceSet, if any.
         // All calls to methods on the ResourceSet after a call to close may 
         // fail.  Close is guaranteed to be safely callable multiple times on a