Update Chrome/Safari versions for sandbox="allow-pointer-lock"

This was implemented in WebKit 537.6:
WebKit/WebKit@73c18e6
https://github.com/WebKit/WebKit/blob/73c18e62d7b18a7ad8c626be054f7a3845e53506/Source/WebCore/Configurations/Version.xcconfig

That maps to Chrome 23 and Safari 7.

Those versions need to be clamped to support for requestPointerLock(),
which is Chrome 22 and Safari 10.1. Pointer lock isn't supported on iOS.

All in all: Chrome 23 and Safari 10.1.

html/elements/iframe.json

@@ -875,7 +875,7 @@
               ],
               "support": {
                 "chrome": {
-                  "version_added": "≤49"
+                  "version_added": "23"
                 },
                 "chrome_android": "mirror",
                 "edge": "mirror",
@@ -890,7 +890,7 @@
                 "opera": "mirror",
                 "opera_android": "mirror",
                 "safari": {
-                  "version_added": "≤10.1"
+                  "version_added": "10.1"
                 },
                 "safari_ios": "mirror",
                 "samsunginternet_android": "mirror",