Drop redundant null checks in SVGListPropertyTearOffHelper

Source/core/svg/properties/SVGListPropertyTearOffHelper.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 88 matching lines @@
 
     PassRefPtrWillBeRawPtr<ItemTearOffType> initialize(PassRefPtrWillBeRawPtr<ItemTearOffType> passItem, ExceptionState& exceptionState)
     {
         RefPtrWillBeRawPtr<ItemTearOffType> item = passItem;
 
         if (toDerived()->isImmutable()) {
             exceptionState.throwDOMException(NoModificationAllowedError, "The object is read-only.");
             return nullptr;
         }
 
-        if (!item) {
-            exceptionState.throwTypeError("Lists must be initialized with a valid item.");
-            return nullptr;
-        }
+        ASSERT(item);
 
         RefPtrWillBeRawPtr<ItemPropertyType> value = toDerived()->target()->initialize(getValueForInsertionFromTearOff(item));
         toDerived()->commitChange();
 
         return createItemTearOff(value.release());
     }
 
     PassRefPtrWillBeRawPtr<ItemTearOffType> getItem(unsigned long index, ExceptionState& exceptionState)
     {
         RefPtrWillBeRawPtr<ItemPropertyType> value = toDerived()->target()->getItem(index, exceptionState);
         return createItemTearOff(value.release());
     }
 
     PassRefPtrWillBeRawPtr<ItemTearOffType> insertItemBefore(PassRefPtrWillBeRawPtr<ItemTearOffType> passItem, unsigned long index, ExceptionState& exceptionState)
     {
         RefPtrWillBeRawPtr<ItemTearOffType> item = passItem;
 
         if (toDerived()->isImmutable()) {
             exceptionState.throwDOMException(NoModificationAllowedError, "The object is read-only.");
             return nullptr;
         }
 
-        if (!item) {
-            exceptionState.throwTypeError("An invalid item cannot be inserted to a list.");
-            return nullptr;
-        }
+        ASSERT(item);
 
         RefPtrWillBeRawPtr<ItemPropertyType> value = toDerived()->target()->insertItemBefore(getValueForInsertionFromTearOff(item), index);
         toDerived()->commitChange();
 
         return createItemTearOff(value.release());
     }
 
     PassRefPtrWillBeRawPtr<ItemTearOffType> replaceItem(PassRefPtrWillBeRawPtr<ItemTearOffType> passItem, unsigned long index, ExceptionState& exceptionState)
     {
         RefPtrWillBeRawPtr<ItemTearOffType> item = passItem;
 
         if (toDerived()->isImmutable()) {
             exceptionState.throwDOMException(NoModificationAllowedError, "The object is read-only.");
             return nullptr;
         }
 
-        if (!item) {
-            exceptionState.throwTypeError("An invalid item cannot be replaced with an existing list item.");
-            return nullptr;
-        }
+        ASSERT(item);
 
         RefPtrWillBeRawPtr<ItemPropertyType> value = toDerived()->target()->replaceItem(getValueForInsertionFromTearOff(item), index, exceptionState);
         toDerived()->commitChange();
 
         return createItemTearOff(value.release());
     }
 
     bool anonymousIndexedSetter(unsigned index, PassRefPtrWillBeRawPtr<ItemTearOffType> passItem, ExceptionState& exceptionState)
     {
         replaceItem(passItem, index, exceptionState);
@@ skipping 10 matching lines @@
 
     PassRefPtrWillBeRawPtr<ItemTearOffType> appendItem(PassRefPtrWillBeRawPtr<ItemTearOffType> passItem, ExceptionState& exceptionState)
     {
         RefPtrWillBeRawPtr<ItemTearOffType> item = passItem;
 
         if (toDerived()->isImmutable()) {
             exceptionState.throwDOMException(NoModificationAllowedError, "The object is read-only.");
             return nullptr;
         }
 
-        if (!item) {
-            exceptionState.throwTypeError("An invalid item cannot be appended to a list.");
-            return nullptr;
-        }
+        ASSERT(item);
 
         RefPtrWillBeRawPtr<ItemPropertyType> value = toDerived()->target()->appendItem(getValueForInsertionFromTearOff(item));
         toDerived()->commitChange();
 
         return createItemTearOff(value.release());
     }
 
 protected:
     SVGListPropertyTearOffHelper(PassRefPtrWillBeRawPtr<ListPropertyType> target, SVGElement* contextElement, PropertyIsAnimValType propertyIsAnimVal, const QualifiedName& attributeName = QualifiedName::null())
         : SVGPropertyTearOff<ListPropertyType>(target, contextElement, propertyIsAnimVal, attributeName)
@@ skipping 16 matching lines @@
         return ItemTraits::createTearOff(value, 0, PropertyIsNotAnimVal, QualifiedName::null());
     }
 
 private:
     Derived* toDerived() { return static_cast<Derived*>(this); }
 };
 
 }
 
 #endif // SVGListPropertyTearOffHelper_h