Add WPT tests for registerProtocolHandler and 'web+' schemes

This is a follow-up of [1] where the validation on the web and browser
processes have been unified. Tests for 'web+' have been added to
ProtocolHandlerRegistryTest (browser process). This CL adds similar and
more complete checks to the existing WPT test (web process).

The relevant section from the specification says [2]:

* Set scheme to scheme, converted to ASCII lowercase.
* If scheme is neither a safelisted scheme nor a string starting with
  "web+" followed by one or more ASCII lower alphas, then throw a
  "SecurityError" DOMException.

Bug: 971917, 952974, 627682

[1] https://chromium-review.googlesource.com/c/chromium/src/+/2362802
[2] https://html.spec.whatwg.org/multipage/system-state.html#normalize-protocol-handler-parameters

Change-Id: I769048bd4db6883a75d4237f20f23aa61452d732
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2371632Reviewed-by: Gyuyoung Kim <gyuyoung@igalia.com>
Commit-Queue: Frédéric Wang <fwang@igalia.com>
Cr-Commit-Position: refs/heads/master@{#801004}

third_party/blink/web_tests/external/wpt/html/webappapis/system-state-and-capabilities/the-navigator-object/protocol.https.html

@@ -140,8 +140,16 @@ test(() => {
   /* web+ prefixed schemes must be followed by 1+ ascii alphas */
   'web+',
   'web+1',
+  'web+namewithid123',
+  'web+namewithtrailingspace ',
+  'web+préfixewithaccent',     // é is not ascii alpha
+  'web+Kelvinsign',            // ASCII-lower KELVIN SIGN is not k
+  'web+latinsmallletterlongſ', // ASCII-lower LATIN SMALL LETTER LONG S is not s
   'web+dots.are.forbidden',
   'web+dashes-are-forbidden',
+  'web+underscores_are_forbidden',
+  'web+spaces are forbidden',
+  'web+non*alpha*are*forbidden',
   'web+digits123areforbidden',
 ].forEach(scheme => {
   test(() => {
@@ -191,6 +199,7 @@ test(() => {
   'WebCAL',
   'WTAI',
   'web+myprotocol',
+  'web+abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', // all alphas
   'web+UpperCasedIsLowercased',
   'WEB+seeabove',
   'WeB+SeEaBoVe'