Selection API: collapse(), setBaseAndExtent(), and extend() don't need to have code to check negati…

third_party/WebKit/Source/core/editing/DOMSelection.cpp

 /*
  * Copyright (C) 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2012 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 206 matching lines @@
   // 1. If node is null, this method must behave identically as
   // removeAllRanges() and abort these steps.
   if (!node) {
     UseCounter::count(frame(), UseCounter::SelectionCollapseNull);
     frame()->selection().clear();
     return;
   }
 
   // 2. The method must throw an IndexSizeError exception if offset is longer
   // than node's length ([DOM4]) and abort these steps.
-  if (offset < 0) {
-    exceptionState.throwDOMException(
-        IndexSizeError, String::number(offset) + " is not a valid offset.");
-    return;
-  }
   Range::checkNodeWOffset(node, offset, exceptionState);
   if (exceptionState.hadException())
     return;
 
   // 3. If node's root is not the document associated with the context object,
   // abort these steps.
   if (!isValidForPosition(node))
     return;
 
   // 4. Otherwise, let newRange be a new range.
@@ skipping 73 matching lines @@
 }
 
 void DOMSelection::setBaseAndExtent(Node* baseNode,
                                     int baseOffset,
                                     Node* extentNode,
                                     int extentOffset,
                                     ExceptionState& exceptionState) {
   if (!isAvailable())
     return;
 
-  if (baseOffset < 0) {
-    exceptionState.throwDOMException(
-        IndexSizeError,
-        String::number(baseOffset) + " is not a valid base offset.");
-    return;
-  }
-
-  if (extentOffset < 0) {
-    exceptionState.throwDOMException(
-        IndexSizeError,
-        String::number(extentOffset) + " is not a valid extent offset.");
-    return;
-  }
-
   // TODO(editing-dev): Behavior on where base or extent is null is still
   // under discussion: https://github.com/w3c/selection-api/issues/72
   if (!baseNode) {
     UseCounter::count(frame(), UseCounter::SelectionSetBaseAndExtentNull);
     frame()->selection().clear();
     return;
   }
   if (!extentNode) {
     UseCounter::count(frame(), UseCounter::SelectionSetBaseAndExtentNull);
     extentOffset = 0;
@@ skipping 115 matching lines @@
     return;
 
   // 2. If the context object is empty, throw an InvalidStateError exception and
   // abort these steps.
   if (rangeCount() == 0) {
     exceptionState.throwDOMException(
         InvalidStateError, "This Selection object doesn't have any Ranges.");
     return;
   }
 
-  if (offset < 0) {
-    exceptionState.throwDOMException(
-        IndexSizeError, String::number(offset) + " is not a valid offset.");
-    return;
-  }
   Range::checkNodeWOffset(node, offset, exceptionState);
   if (exceptionState.hadException())
     return;
 
   // 3. Let oldAnchor and oldFocus be the context object's anchor and focus, and
   // let newFocus be the boundary point (node, offset).
   const Position& oldAnchor = anchorPosition();
   // TODO(tkent): Diagnostic checks for crbug.com/693578.  They should be
   // removed before M58 branch.
   if (oldAnchor.isNull()) {
@@ skipping 348 matching lines @@
     m_treeScope->document().addConsoleMessage(
         ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, message));
 }
 
 DEFINE_TRACE(DOMSelection) {
   visitor->trace(m_treeScope);
   ContextClient::trace(visitor);
 }
 
 }  // namespace blink