dart2js: Remove isD8 and isJsShell functions.

sdk/lib/_internal/compiler/js_lib/js_helper.dart

Index: sdk/lib/_internal/compiler/js_lib/js_helper.dart
diff --git a/sdk/lib/_internal/compiler/js_lib/js_helper.dart b/sdk/lib/_internal/compiler/js_lib/js_helper.dart
index f0d7ebf803f1ff4c4edb2752038a87e466b39232..1c5468aa0f3cab61837536b8417c6cc9e36f1a63 100644
--- a/sdk/lib/_internal/compiler/js_lib/js_helper.dart
+++ b/sdk/lib/_internal/compiler/js_lib/js_helper.dart
@@ -829,18 +829,6 @@ class Primitives {
   static int timerFrequency;
   static Function timerTicks;
 
-  static bool get isD8 {
-    return JS('bool',
-              'typeof version == "function"'
-              ' && typeof os == "object" && "setenv" in os');
-  }
-
-  static bool get isJsshell {
-    return JS('bool',
-              'typeof version == "function" '
-              ' && typeof os == "object" && "getenv" in os');
-  }
-
   static String currentUri() {
     requiresPreamble();
     // In a browser return self.location.href.