[Truffle] Removed compilation guards.

Since moving to Rubinius's Enumerable, these are hot paths that PE in benchmarks.

Author: nirvdrum

core/src/main/java/org/jruby/truffle/nodes/core/KernelNodes.java

@@ -339,8 +339,6 @@ public BlockGivenNode(BlockGivenNode prev) {
 
         @Specialization
         public boolean blockGiven() {
-            notDesignedForCompilation();
-
             return RubyArguments.getBlock(Truffle.getRuntime().getCallerFrame().getFrame(FrameInstance.FrameAccess.READ_ONLY, false).getArguments()) != null;
         }
     }

core/src/main/java/org/jruby/truffle/nodes/rubinius/RubiniusSingleBlockArgNode.java

@@ -28,8 +28,6 @@ public RubiniusSingleBlockArgNode(RubyContext context, SourceSection sourceSecti
 
     @Override
     public Object execute(VirtualFrame frame) {
-        notDesignedForCompilation();
-
         /**
          * This is our implementation of Rubinius.single_block_arg.
          *
@@ -52,7 +50,7 @@ public Object execute(VirtualFrame frame) {
             } else {
                 Object[] extractedArguments = RubyArguments.extractUserArguments(frame.getArguments());
 
-                return RubyArray.fromObjects(getContext().getCoreLibrary().getArrayClass(), extractedArguments);
+                return new RubyArray(getContext().getCoreLibrary().getArrayClass(), extractedArguments, userArgumentCount);
             }
         }
     }