Add experimental Support for DOM3 KeyboardEvent key value

Source/web/WebInputEventConversion.cpp

Index: Source/web/WebInputEventConversion.cpp
diff --git a/Source/web/WebInputEventConversion.cpp b/Source/web/WebInputEventConversion.cpp
index a4a3afa831a8f3cc69bf6cb805cc64fcfe59a630..0e1c6f652e93519695f2bc16b54a9e6b4760811a 100644
--- a/Source/web/WebInputEventConversion.cpp
+++ b/Source/web/WebInputEventConversion.cpp
@@ -319,6 +319,7 @@ PlatformKeyboardEventBuilder::PlatformKeyboardEventBuilder(const WebKeyboardEven
     m_isKeypad = (e.modifiers & WebInputEvent::IsKeyPad);
     m_isSystemKey = e.isSystemKey;
     m_code = Platform::current()->domCodeStringFromEnum(e.domCode);
+    m_key = Platform::current()->domKeyStringFromEnum(e.domKey);
 
     m_modifiers = toPlatformEventModifiers(e.modifiers);
 
@@ -677,6 +678,7 @@ WebKeyboardEventBuilder::WebKeyboardEventBuilder(const KeyboardEvent& event)
         return;
     nativeKeyCode = event.keyEvent()->nativeVirtualKeyCode();
     domCode = Platform::current()->domEnumFromCodeString(event.keyEvent()->code());
+    domKey = Platform::current()->domEnumFromKeyString(event.keyEvent()->key());
     unsigned numberOfCharacters = std::min(event.keyEvent()->text().length(), static_cast<unsigned>(textLengthCap));
     for (unsigned i = 0; i < numberOfCharacters; ++i) {
         text[i] = event.keyEvent()->text()[i];
@@ -712,6 +714,7 @@ WebKeyboardEventBuilder::WebKeyboardEventBuilder(const PlatformKeyboardEvent& ev
     isSystemKey = event.isSystemKey();
     nativeKeyCode = event.nativeVirtualKeyCode();
     domCode = Platform::current()->domEnumFromCodeString(event.code());
+    domKey = Platform::current()->domEnumFromKeyString(event.key());
 
     windowsKeyCode = windowsKeyCodeWithoutLocation(event.windowsVirtualKeyCode());
     modifiers |= locationModifiersFromWindowsKeyCode(event.windowsVirtualKeyCode());