Update initial support for <iframe sandbox> in WebKit

This was implemented without a flag, and with the reflected IDL
attribute, in WebKit 532.6:
WebKit/WebKit@c205c4e
https://github.com/WebKit/WebKit/blob/c205c4e7d40da38c5009df548c2316a358a4fca7/WebCore/Configurations/Version.xcconfig

That maps to Chrome 5 + Safari 5 + iOS 4, which also matches exactly
earlier updates based on collector test results:
mdn#7243
mdn#7290
mdn#7402

The handled attribute tokens were "allow-same-origin", "allow-forms",
and "allow-scripts", so update that data to match.

html/elements/iframe.json

@@ -701,7 +701,7 @@
             "spec_url": "https://html.spec.whatwg.org/multipage/iframe-embed-object.html#attr-iframe-sandbox",
             "support": {
               "chrome": {
-                "version_added": "4"
+                "version_added": "5"
               },
               "chrome_android": "mirror",
               "edge": {
@@ -720,7 +720,9 @@
               "safari": {
                 "version_added": "5"
               },
-              "safari_ios": "mirror",
+              "safari_ios": {
+                "version_added": "4"
+              },
               "samsunginternet_android": "mirror",
               "webview_android": "mirror"
             },
@@ -770,7 +772,7 @@
               "spec_url": "https://html.spec.whatwg.org/multipage/browsers.html#attr-iframe-sandbox-allow-forms",
               "support": {
                 "chrome": {
-                  "version_added": "≤49"
+                  "version_added": "5"
                 },
                 "chrome_android": "mirror",
                 "edge": "mirror",
@@ -785,9 +787,11 @@
                 "opera": "mirror",
                 "opera_android": "mirror",
                 "safari": {
-                  "version_added": "≤10.1"
+                  "version_added": "5"
+                },
+                "safari_ios": {
+                  "version_added": "4"
                 },
-                "safari_ios": "mirror",
                 "samsunginternet_android": "mirror",
                 "webview_android": "mirror"
               },
@@ -1017,7 +1021,7 @@
               "spec_url": "https://html.spec.whatwg.org/multipage/browsers.html#attr-iframe-sandbox-allow-same-origin",
               "support": {
                 "chrome": {
-                  "version_added": "≤49",
+                  "version_added": "5",
                   "notes": "Chrome 70 and earlier block script execution without <code>allow-scripts</code>, even if <code>allow-same-origin</code> is set. For example, any bound handlers for click events of nodes inside an iframe throw an error for blocked script execution."
                 },
                 "chrome_android": "mirror",
@@ -1033,10 +1037,13 @@
                 "opera": "mirror",
                 "opera_android": "mirror",
                 "safari": {
-                  "version_added": "≤10.1",
+                  "version_added": "5",
+                  "notes": "Safari blocks script execution without <code>allow-scripts</code> even if <code>allow-same-origin</code> is set. For example, any bound handlers for click events of nodes inside an iframe throw an error for blocked script execution."
+                },
+                "safari_ios": {
+                  "version_added": "4",
                   "notes": "Safari blocks script execution without <code>allow-scripts</code> even if <code>allow-same-origin</code> is set. For example, any bound handlers for click events of nodes inside an iframe throw an error for blocked script execution."
                 },
-                "safari_ios": "mirror",
                 "samsunginternet_android": "mirror",
                 "webview_android": "mirror"
               },
@@ -1053,7 +1060,7 @@
               "spec_url": "https://html.spec.whatwg.org/multipage/browsers.html#attr-iframe-sandbox-allow-scripts",
               "support": {
                 "chrome": {
-                  "version_added": "≤49"
+                  "version_added": "5"
                 },
                 "chrome_android": "mirror",
                 "edge": "mirror",
@@ -1068,9 +1075,11 @@
                 "opera": "mirror",
                 "opera_android": "mirror",
                 "safari": {
-                  "version_added": "≤10.1"
+                  "version_added": "5"
+                },
+                "safari_ios": {
+                  "version_added": "4"
                 },
-                "safari_ios": "mirror",
                 "samsunginternet_android": "mirror",
                 "webview_android": "mirror"
               },