Drop [LegacyInterfaceTypeChecking] where trivial in core/

third_party/WebKit/Source/core/dom/TreeWalker.cpp

Index: third_party/WebKit/Source/core/dom/TreeWalker.cpp
diff --git a/third_party/WebKit/Source/core/dom/TreeWalker.cpp b/third_party/WebKit/Source/core/dom/TreeWalker.cpp
index aa8fbbff13849d807dcee0645723e0969d48b757..496d13a0571edc7cb0749cec4d41ddb12191e042 100644
--- a/third_party/WebKit/Source/core/dom/TreeWalker.cpp
+++ b/third_party/WebKit/Source/core/dom/TreeWalker.cpp
@@ -39,12 +39,9 @@ TreeWalker::TreeWalker(PassRefPtrWillBeRawPtr<Node> rootNode, unsigned whatToSho
 {
 }
 
-void TreeWalker::setCurrentNode(PassRefPtrWillBeRawPtr<Node> node, ExceptionState& exceptionState)
+void TreeWalker::setCurrentNode(PassRefPtrWillBeRawPtr<Node> node)
 {
-    if (!node) {
-        exceptionState.throwDOMException(NotSupportedError, ExceptionMessages::argumentNullOrIncorrectType(1, "Node"));
-        return;
-    }
+    ASSERT(node);
     m_current = node;
 }