Add support for TextInputType.url (#3730)

Adds support for requesting a platform keyboard optimised for entering
URLs.

shell/platform/android/io/flutter/plugin/editing/TextInputPlugin.java

@@ -84,6 +84,8 @@ public class TextInputPlugin implements MethodCallHandler {
         int textType = InputType.TYPE_CLASS_TEXT;
         if (inputType.equals("TextInputType.emailAddress"))
             textType |= InputType.TYPE_TEXT_VARIATION_EMAIL_ADDRESS;
+        else if (inputType.equals("TextInputType.url"))
+            textType |= InputType.TYPE_TEXT_VARIATION_URI;
         if (obscureText)
             textType |= InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS;
         return textType;

shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.mm

@@ -18,6 +18,8 @@ static UIKeyboardType ToUIKeyboardType(NSString* inputType) {
     return UIKeyboardTypePhonePad;
   if ([inputType isEqualToString:@"TextInputType.emailAddress"])
     return UIKeyboardTypeEmailAddress;
+  if ([inputType isEqualToString:@"TextInputType.url"])
+    return UIKeyboardTypeURL;
   return UIKeyboardTypeDefault;
 }