Make oldFields mapping hardcoded to speed up system

The mapping came with Magneto 1.6 to provide a backward compatibility
for old (pre 1.6) db field names.
Now the mapping is hardcoded in the class instead of saved
in the configuration.
This improves performance as Magento will not create tons of objects for
every new product/order/... entities.

Related: #920

Author: tmotyl

app/code/core/Mage/Catalog/Model/Product.php

@@ -360,7 +360,6 @@ protected function _construct()
      */
     protected function _initOldFieldsMap()
     {
-        $this->_oldFieldsMap = Mage::helper('catalog')->getOldFieldMap();
         return $this;
     }
 

app/code/core/Mage/CatalogInventory/Model/Stock/Item.php

@@ -177,6 +177,7 @@ protected function _construct()
      */
     protected function _initOldFieldsMap()
     {
+        // pre 1.6 fields names, old => new
         $this->_oldFieldsMap = array(
             'stock_status_changed_automatically' => 'stock_status_changed_auto',
             'use_config_enable_qty_increments'   => 'use_config_enable_qty_inc'

app/code/core/Mage/Sales/Model/Order.php

@@ -526,7 +526,12 @@ protected function _construct()
      */
     protected function _initOldFieldsMap()
     {
-        $this->_oldFieldsMap = Mage::helper('sales')->getOldFieldMap('order');
+        // pre 1.6 fields names, old => new
+        $this->_oldFieldsMap = [
+            'payment_authorization_expiration' => 'payment_auth_expiration',
+            'forced_do_shipment_with_invoice' => 'forced_shipment_with_invoice',
+            'base_shipping_hidden_tax_amount' => 'base_shipping_hidden_tax_amnt',
+        ];
         return $this;
     }
 

app/code/core/Mage/Sales/Model/Order/Address.php

@@ -112,7 +112,6 @@ protected function _construct()
      */
     protected function _initOldFieldsMap()
     {
-        $this->_oldFieldsMap = Mage::helper('sales')->getOldFieldMap('order_address');
         return $this;
     }
 

app/code/core/Mage/Sales/Model/Order/Creditmemo.php

@@ -224,7 +224,6 @@ protected function _construct()
      */
     protected function _initOldFieldsMap()
     {
-        $this->_oldFieldsMap = Mage::helper('sales')->getOldFieldMap('order_creditmemo');
         return $this;
     }
 

app/code/core/Mage/Sales/Model/Order/Creditmemo/Item.php

@@ -153,7 +153,10 @@ public function setCreditmemo(Mage_Sales_Model_Order_Creditmemo $creditmemo)
      */
     protected function _initOldFieldsMap()
     {
-        $this->_oldFieldsMap = Mage::helper('sales')->getOldFieldMap('creditmemo_item');
+        // pre 1.6 fields names, old => new
+        $this->_oldFieldsMap = [
+            'base_weee_tax_applied_row_amount' => 'base_weee_tax_applied_row_amnt',
+        ];
         return $this;
     }
 

app/code/core/Mage/Sales/Model/Order/Invoice.php

@@ -223,7 +223,6 @@ protected function _construct()
      */
     protected function _initOldFieldsMap()
     {
-        $this->_oldFieldsMap = Mage::helper('sales')->getOldFieldMap('order_invoice');
         return $this;
     }
 

app/code/core/Mage/Sales/Model/Order/Invoice/Item.php

@@ -125,7 +125,10 @@ public function _construct()
      */
     protected function _initOldFieldsMap()
     {
-        $this->_oldFieldsMap = Mage::helper('sales')->getOldFieldMap('invoice_item');
+        // pre 1.6 fields names, old => new
+        $this->_oldFieldsMap = [
+            'base_weee_tax_applied_row_amount' => 'base_weee_tax_applied_row_amnt',
+        ];
         return $this;
     }
     /**

app/code/core/Mage/Sales/Model/Order/Item.php

@@ -246,7 +246,10 @@ protected function _construct()
      */
     protected function _initOldFieldsMap()
     {
-        $this->_oldFieldsMap = Mage::helper('sales')->getOldFieldMap('order_item');
+        // pre 1.6 fields names, old => new
+        $this->_oldFieldsMap = [
+            'base_weee_tax_applied_row_amount' => 'base_weee_tax_applied_row_amnt',
+        ];
         return $this;
     }
 

app/code/core/Mage/Sales/Model/Order/Shipment.php

@@ -127,7 +127,6 @@ protected function _construct()
      */
     protected function _initOldFieldsMap()
     {
-        $this->_oldFieldsMap = Mage::helper('sales')->getOldFieldMap('order_shipment');
         return $this;
     }