Remove hasnling false scopes

Remove lazy load stacks and instead only create a new scope when a tag is known to need one

lib/liquid/context.rb

@@ -25,8 +25,6 @@ module Liquid
       @resource_limits  = resource_limits || ResourceLimits.new(Template.default_resource_limits)
       squash_instance_assigns_with_environments
 
-      @this_stack_used = false
-
       self.exception_renderer = Template.default_exception_renderer
       if rethrow_errors
         self.exception_renderer = ->(e) { raise }
@@ -111,19 +109,11 @@ module Liquid
     #   end
     #
     #   context['var]  #=> nil
-    def stack(new_scope = nil)
+    def stack(new_scope = {})
-      old_stack_used = @this_stack_used
-      if new_scope
       push(new_scope)
-        @this_stack_used = true
-      else
-        @this_stack_used = false
-      end
-
       yield
     ensure
-      pop if @this_stack_used
+      pop
-      @this_stack_used = old_stack_used
     end
 
     def clear_instance_assigns
@@ -132,10 +122,6 @@ module Liquid
 
     # Only allow String, Numeric, Hash, Array, Proc, Boolean or <tt>Liquid::Drop</tt>
     def []=(key, value)
-      unless @this_stack_used
-        @this_stack_used = true
-        push({})
-      end
       @scopes[0][key] = value
     end
 

lib/liquid/tags/case.rb

@@ -39,7 +39,6 @@ module Liquid
     end
 
     def render_to_output_buffer(context, output)
-      context.stack do
       execute_else_block = true
 
       @blocks.each do |block|
@@ -50,7 +49,6 @@ module Liquid
           block.attachment.render_to_output_buffer(context, output)
         end
       end
-      end
 
       output
     end

lib/liquid/tags/cycle.rb

@@ -34,7 +34,6 @@ module Liquid
     def render_to_output_buffer(context, output)
       context.registers[:cycle] ||= {}
 
-      context.stack do
       key = context.evaluate(@name)
       iteration = context.registers[:cycle][key].to_i
 
@@ -51,7 +50,6 @@ module Liquid
       iteration += 1
       iteration  = 0 if iteration >= @variables.size
       context.registers[:cycle][key] = iteration
-      end
 
       output
     end

lib/liquid/tags/if.rb

@@ -40,13 +40,11 @@ module Liquid
     end
 
     def render_to_output_buffer(context, output)
-      context.stack do
       @blocks.each do |block|
         if block.evaluate(context)
           return block.attachment.render_to_output_buffer(context, output)
         end
       end
-      end
 
       output
     end

lib/liquid/tags/ifchanged.rb

@@ -1,7 +1,6 @@
 module Liquid
   class Ifchanged < Block
     def render_to_output_buffer(context, output)
-      context.stack do
       block_output = ''
       super(context, block_output)
 
@@ -9,7 +8,6 @@ module Liquid
         context.registers[:ifchanged] = block_output
         output << block_output
       end
-      end
 
       output
     end

lib/liquid/tags/unless.rb

@@ -7,7 +7,6 @@ module Liquid
   #
   class Unless < If
     def render_to_output_buffer(context, output)
-      context.stack do
       # First condition is interpreted backwards ( if not )
       first_block = @blocks.first
       unless first_block.evaluate(context)
@@ -20,7 +19,6 @@ module Liquid
           return block.attachment.render_to_output_buffer(context, output)
         end
       end
-      end
 
       output
     end