Simplify BlockNode by removing intermediate MustacheNode

lib/handlebars/compiler/compiler.js

@@ -108,7 +108,7 @@ Compiler.prototype = {
   },
 
   block: function(block) {
-    var mustache = block.mustache,
+    var sexpr = block.sexpr,
         program = block.program,
         inverse = block.inverse;
 
@@ -120,7 +120,6 @@ Compiler.prototype = {
       inverse = this.compileProgram(inverse);
     }
 
-    var sexpr = mustache.sexpr;
     var type = this.classifySexpr(sexpr);
 
     if (type === "helper") {