Add experimental Support for DOM3 KeyboardEvent key value

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 4338 matching lines @@
             {
                 "name": "dispatchKeyEvent",
                 "parameters": [
                     { "name": "type", "type": "string", "enum": ["keyDown", "keyUp", "rawKeyDown", "char"], "description": "Type of the key event." },
                     { "name": "modifiers", "type": "integer", "optional": true, "description": "Bit field representing pressed modifier keys. Alt=1, Ctrl=2, Meta/Command=4, Shift=8 (default: 0)." },
                     { "name": "timestamp", "type": "number", "optional": true, "description": "Time at which the event occurred. Measured in UTC time in seconds since January 1, 1970 (default: current time)." },
                     { "name": "text", "type": "string", "optional": true, "description": "Text as generated by processing a virtual key code with a keyboard layout. Not needed for for <code>keyUp</code> and <code>rawKeyDown</code> events (default: \"\")" },
                     { "name": "unmodifiedText", "type": "string", "optional": true, "description": "Text that would have been generated by the keyboard if no modifiers were pressed (except for shift). Useful for shortcut (accelerator) key handling (default: \"\")." },
                     { "name": "keyIdentifier", "type": "string", "optional": true, "description": "Unique key identifier (e.g., 'U+0041') (default: \"\")." },
                     { "name": "code", "type": "string", "optional": true, "description": "Unique DOM defined string value for each physical key (e.g., 'KeyA') (default: \"\")." },
+                    { "name": "key", "type": "string", "optional": true, "description": "Unique DOM defined string value describing the meaning of the key in the context of active modifiers, keyboard layout, etc (e.g., 'AltGr') (default: \"\")." },
                     { "name": "windowsVirtualKeyCode", "type": "integer", "optional": true, "description": "Windows virtual key code (default: 0)." },
                     { "name": "nativeVirtualKeyCode", "type": "integer", "optional": true, "description": "Native virtual key code (default: 0)." },
                     { "name": "autoRepeat", "type": "boolean", "optional": true, "description": "Whether the event was generated from auto repeat (default: false)." },
                     { "name": "isKeypad", "type": "boolean", "optional": true, "description": "Whether the event was generated from the keypad (default: false)." },
                     { "name": "isSystemKey", "type": "boolean", "optional": true, "description": "Whether the event was a system key event (default: false)." }
                 ],
                 "description": "Dispatches a key event to the page."
             },
             {
                 "name": "dispatchMouseEvent",
@@ skipping 524 matching lines @@
                 ],
                 "returns": [
                     { "name": "accessibilityNode", "$ref": "AXNode", "description": "The <code>Accessibility.AXNode</code> for this DOM node, if it exists." }
                 ],
                 "description": "Fetches the accessibility node for this DOM node, if it exists.",
                 "hidden": true
             }
         ]
     }]
 }