Add feature for isSecureContext (#2717)

Author: ddbeck

features/is-secure-context.yml

@@ -0,0 +1,6 @@
+name: isSecureContext
+description: The `isSecureContext` global property is a boolean for whether the current browsing context is secure. This is primarily a check that the page has been served over an HTTPS URL.
+spec: https://html.spec.whatwg.org/multipage/webappapis.html#dom-issecurecontext-dev
+compat_features:
+  - api.isSecureContext
+  - api.isSecureContext.worker_support

features/is-secure-context.yml.dist

@@ -0,0 +1,42 @@
+# Generated from: is-secure-context.yml
+# Do not edit this file by hand. Edit the source file instead!
+
+status:
+  baseline: high
+  baseline_low_date: 2018-04-12
+  baseline_high_date: 2020-10-12
+  support:
+    chrome: "55"
+    chrome_android: "55"
+    edge: "15"
+    firefox: "52"
+    firefox_android: "52"
+    safari: "11.1"
+    safari_ios: "11.3"
+compat_features:
+  # baseline: high
+  # baseline_low_date: 2018-04-12
+  # baseline_high_date: 2020-10-12
+  # support:
+  #   chrome: "47"
+  #   chrome_android: "47"
+  #   edge: "15"
+  #   firefox: "49"
+  #   firefox_android: "49"
+  #   safari: "11.1"
+  #   safari_ios: "11.3"
+  - api.isSecureContext
+
+  # ⬇️ Same status as overall feature ⬇️
+  # baseline: high
+  # baseline_low_date: 2018-04-12
+  # baseline_high_date: 2020-10-12
+  # support:
+  #   chrome: "55"
+  #   chrome_android: "55"
+  #   edge: "15"
+  #   firefox: "52"
+  #   firefox_android: "52"
+  #   safari: "11.1"
+  #   safari_ios: "11.3"
+  - api.isSecureContext.worker_support