Merge branch 'master' into optimize_mcode

mcode.cm

@@ -2837,6 +2837,7 @@ var mcode = function(ast) {
     var result = null
     var saved_label = 0
     var saved_func = 0
+    var captured_this = 0
 
     push(parent_states, saved)
 
@@ -2889,6 +2890,13 @@ var mcode = function(ast) {
       s_max_slot = s_next_temp_slot
     }
 
+    // Arrow functions capture the enclosing this via closure
+    if (is_arrow) {
+      captured_this = alloc_slot()
+      emit_3("get", captured_this, saved.this_slot, 1)
+      s_this_slot = captured_this
+    }
+
     // Default parameter initialization
     ps = 1
     _i = 0