Run ContextPolicyTest, ContextPolyglotAccessTest with isolated context.

Author: jchalou

truffle/src/com.oracle.truffle.api.test/src/com/oracle/truffle/api/test/polyglot/ByteSequenceTest.java

@@ -75,6 +75,9 @@ public byte byteAt(int index) {
 
     @BeforeClass
     public static void runWithWeakEncapsulationOnly() {
+        /*
+         * This test does not use polyglot context, no point running it with isolated context.
+         */
         TruffleTestAssumptions.assumeWeakEncapsulation();
     }