Implement selector contextualization for keyframe rules

Fixes sass#947

ast.hpp

@@ -431,10 +431,10 @@ namespace Sass {
   // Keyframe-rules -- the child blocks of "@keyframes" nodes.
   ///////////////////////////////////////////////////////////////////////
   class Keyframe_Rule : public Has_Block {
-    ADD_PROPERTY(String*, rules);
+    ADD_PROPERTY(Selector*, selector);
   public:
     Keyframe_Rule(ParserState pstate, Block* b)
-    : Has_Block(pstate, b), rules_(0)
+    : Has_Block(pstate, b), selector_(0)
     { statement_type(KEYFRAMERULE); }
     ATTACH_OPERATIONS();
   };

cssize.cpp

@@ -87,7 +87,7 @@ namespace Sass {
 
     Keyframe_Rule* rr = new (ctx.mem) Keyframe_Rule(r->pstate(),
                                                     r->block()->perform(this)->block());
-    if (r->rules()) rr->rules(r->rules());
+    if (r->selector()) rr->selector(r->selector());
 
     return debubble(rr->block(), rr)->block();
   }

debugger.hpp

@@ -219,6 +219,11 @@ inline void debug_ast(AST_Node* node, string ind = "", Env* env = 0)
     cerr << ind << "Declaration " << block << " " << block->tabs() << endl;
     debug_ast(block->property(), ind + " prop: ", env);
     debug_ast(block->value(), ind + " value: ", env);
+  } else if (dynamic_cast<Keyframe_Rule*>(node)) {
+    Keyframe_Rule* has_block = dynamic_cast<Keyframe_Rule*>(node);
+    cerr << ind << "Keyframe_Rule " << has_block << " " << has_block->tabs() << endl;
+    if (has_block->selector()) debug_ast(has_block->selector(), ind + "@");
+    if (has_block->block()) for(auto i : has_block->block()->elements()) { debug_ast(i, ind + " ", env); }
   } else if (dynamic_cast<At_Rule*>(node)) {
     At_Rule* block = dynamic_cast<At_Rule*>(node);
     cerr << ind << "At_Rule " << block << " [" << block->keyword() << "] " << block->tabs() << endl;

expand.cpp

@@ -47,11 +47,7 @@ namespace Sass {
     if (in_keyframes) {
       To_String to_string;
       Keyframe_Rule* k = new (ctx.mem) Keyframe_Rule(r->pstate(), r->block()->perform(this)->block());
-      if (r->selector()) {
-        string s(r->selector()->perform(eval->with(env, backtrace))->perform(&to_string));
-        String_Constant* ss = new (ctx.mem) String_Constant(r->selector()->pstate(), s);
-        k->rules(ss);
-      }
+      if (r->selector()) k->selector(r->selector()->perform(contextualize->with(0, env, backtrace)));
       in_at_root = old_in_at_root;
       old_in_at_root = false;
       return k;

inspect.cpp

@@ -44,9 +44,8 @@ namespace Sass {
 
   void Inspect::operator()(Keyframe_Rule* rule)
   {
-    append_indentation();
-    if (rule->rules()) rule->rules()->perform(this);
-    rule->block()->perform(this);
+    if (rule->selector()) rule->selector()->perform(this);
+    if (rule->block()) rule->block()->perform(this);
   }
 
   void Inspect::operator()(Propset* propset)

output.cpp

@@ -172,11 +172,10 @@ namespace Sass {
 
   void Output::operator()(Keyframe_Rule* r)
   {
-    String* v = r->rules();
     Block* b = r->block();
+    Selector* v = r->selector();
 
     if (v) {
-      append_indentation();
       v->perform(this);
     }