Change the level of Selection.addRange failure message.

Error -> Warning.

Bug: 697443
Change-Id: Ib4e88bb64cd5f1a533ae88306c47e91ca0606085
Reviewed-on: https://chromium-review.googlesource.com/c/1337216Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608284}

third_party/WebKit/LayoutTests/editing/selection/addRange-failures-expected.txt

-CONSOLE ERROR: line 29: The given range isn't in document.
+CONSOLE WARNING: line 29: addRange(): The given range isn't in document.
 CONSOLE WARNING: line 46: Element.createShadowRoot is deprecated and will be removed in M73, around March 2019. Please use Element.attachShadow instead. See https://www.chromestatus.com/features/4507242028072960 for more details.
 Test error handling of Selection.addRange().
 

third_party/blink/renderer/core/editing/dom_selection.cc

@@ -624,7 +624,7 @@ void DOMSelection::addRange(Range* new_range) {
     return;
 
   if (!new_range->IsConnected()) {
-    AddConsoleError("The given range isn't in document.");
+    AddConsoleWarning("addRange(): The given range isn't in document.");
     return;
   }
 
@@ -832,10 +832,11 @@ bool DOMSelection::IsValidForPosition(Node* node) const {
          node->isConnected();
 }
 
-void DOMSelection::AddConsoleError(const String& message) {
-  if (tree_scope_)
-    tree_scope_->GetDocument().AddConsoleMessage(
-        ConsoleMessage::Create(kJSMessageSource, kErrorMessageLevel, message));
+void DOMSelection::AddConsoleWarning(const String& message) {
+  if (tree_scope_) {
+    tree_scope_->GetDocument().AddConsoleMessage(ConsoleMessage::Create(
+        kJSMessageSource, kWarningMessageLevel, message));
+  }
 }
 
 void DOMSelection::Trace(blink::Visitor* visitor) {

third_party/blink/renderer/core/editing/dom_selection.h

@@ -122,7 +122,7 @@ class CORE_EXPORT DOMSelection final : public ScriptWrappable,
 
   bool IsValidForPosition(Node*) const;
 
-  void AddConsoleError(const String& message);
+  void AddConsoleWarning(const String& message);
   Range* PrimaryRangeOrNull() const;
   EphemeralRange CreateRangeFromSelectionEditor() const;