[Attempt 2] Inform Chrome client of changes to an input's datalist.

Source/core/html/forms/TextFieldInputType.cpp

Index: Source/core/html/forms/TextFieldInputType.cpp
diff --git a/Source/core/html/forms/TextFieldInputType.cpp b/Source/core/html/forms/TextFieldInputType.cpp
index 297f642f4535de4e940117995cd107e93bb947dd..d557727648b5e2223158a3596220f6e17a59fa31 100644
--- a/Source/core/html/forms/TextFieldInputType.cpp
+++ b/Source/core/html/forms/TextFieldInputType.cpp
@@ -327,6 +327,8 @@ void TextFieldInputType::destroyShadowSubtree()
 
 void TextFieldInputType::listAttributeTargetChanged()
 {
+    if (Chrome* chrome = this->chrome())
+        chrome->client().textFieldDataListChanged(element());
     Element* picker = element().userAgentShadowRoot()->getElementById(ShadowElementNames::pickerIndicator());
     bool didHavePickerIndicator = picker;
     bool willHavePickerIndicator = element().hasValidDataListOptions();