Build: Drop Android 4-6 and iOS 7-8, restore iOS 9-11 and Android 7

* Drop support for Android 4-6, and Android Browser,
  require Android 7.0+ which can run Chrome 80.

* Drop support for iOS 7-8,
  require iOS 9+ (we already require Safari 9 for macOS).

.github/workflows/browsers-full.yaml

@@ -9,6 +9,7 @@ on:
   push:
     paths:
       - .github/workflows/browsers-full.yaml
+      - build/browserstack-full.json
 
 jobs:
   run:

build/browserstack-full.json

@@ -39,42 +39,29 @@
       "os": "android",
       "os_version": "10.0"
     },
+    {
+      "os": "android",
+      "os_version": "7.0",
+      "device": "Samsung Galaxy S8",
+      "real_mobile": true
+    },
     {
       "device": "iPhone 8",
       "real_mobile": true,
       "os": "ios",
       "os_version": "12"
-    }
-  ],
-  "@browsers_disabled": [
-    {
-      "@ref": [
-        "https://github.com/browserstack/browserstack-runner/issues/245",
-        "Android 4, Android 5, Android 6"
-      ]
-    },
-    {
-      "@ref": [
-        "https://github.com/browserstack/browserstack-runner/issues/226",
-        "Android 7-10",
-        "iOS 13, 14"
-      ]
     },
     {
-      "device": "Samsung Galaxy S7",
-      "real_mobile": true,
-      "os": "android",
-      "os_version": "6.0"
+      "os": "ios",
+      "os_version": "11.0"
     },
     {
-      "device": null,
       "os": "ios",
-      "os_version": "13"
+      "os_version": "10.3"
     },
     {
-      "device": null,
       "os": "ios",
-      "os_version": "14"
+      "os_version": "9.3"
     }
   ]
 }

src/core.js

@@ -95,7 +95,8 @@ extend(QUnit, {
 
   stack: function (offset) {
     offset = (offset || 0) + 2;
-    // Support Safari: Use temp variable to avoid TCO for consistent cross-browser result
+    // Support Safari: Use temp variable to avoid triggering ES6 Proper Tail Calls,
+    // which ensures a consistent cross-browser result.
     // https://bugs.webkit.org/show_bug.cgi?id=276187
     const source = sourceFromStacktrace(offset);
     return source;

src/core/utilities.js

@@ -74,7 +74,7 @@ export function objectValuesSubset (obj, model) {
   return subset;
 }
 
-// Support: IE 11, iOS 7-8
+// Support: IE 11
 export function extend (a, b, undefOnly, allProperties) {
   for (const prop in b) {
     if (hasOwn.call(b, prop) || allProperties) {

src/globals.js

@@ -63,11 +63,7 @@ export const sessionStorage = (function () {
   }
 }());
 
-// Basic fallback for ES6 Map
-// Support: Safari 7; Map is undefined
-// Support: iOS 8; `new Map(iterable)` is not supported
-//
-// Fallback for ES7 Map#keys
+// Fallback for ES6 Map, `new Map(iterable)`, and ES7 Map#keys
 // Support: IE 11; Map#keys is undefined
 export const StringMap = typeof g.Map === 'function' &&
   typeof g.Map.prototype.keys === 'function' &&