fix incorrect code elimination

fold.cm

@@ -73,6 +73,7 @@ var fold = function(ast) {
     if (k == "record") {
       i = 0
       while (i < length(expr.list)) {
+        if (expr.list[i].computed && !is_pure(expr.list[i].left)) return false
         if (!is_pure(expr.list[i].right)) return false
         i = i + 1
       }
@@ -286,6 +287,7 @@ var fold = function(ast) {
     if (k == "record") {
       i = 0
       while (i < length(expr.list)) {
+        if (expr.list[i].computed) pre_scan_expr_fns(expr.list[i].left)
         pre_scan_expr_fns(expr.list[i].right)
         i = i + 1
       }
@@ -412,6 +414,9 @@ var fold = function(ast) {
     } else if (k == "record") {
       i = 0
       while (i < length(expr.list)) {
+        if (expr.list[i].computed) {
+          expr.list[i].left = fold_expr(expr.list[i].left, fn_nr)
+        }
         expr.list[i].right = fold_expr(expr.list[i].right, fn_nr)
         i = i + 1
       }
@@ -860,6 +865,7 @@ var fold = function(ast) {
       if (k == "record") {
         i = 0
         while (i < length(expr.list)) {
+          if (expr.list[i].computed) walk_expr_for_fns(expr.list[i].left)
           walk_expr_for_fns(expr.list[i].right)
           i = i + 1
         }
@@ -949,6 +955,7 @@ var fold = function(ast) {
       if (k == "record") {
         i = 0
         while (i < length(expr.list)) {
+          if (expr.list[i].computed) collect_expr_intrinsics(expr.list[i].left)
           collect_expr_intrinsics(expr.list[i].right)
           i = i + 1
         }

parse.cm

@@ -364,6 +364,7 @@ var parse = function(tokens, src, filename, tokenizer) {
           advance()
           left = parse_assign_expr()
           pair.left = left
+          pair.computed = true
           if (tok.kind == "]") advance()
           else parse_error(tok, "expected ']' after computed property")
         } else {
@@ -1797,6 +1798,9 @@ var parse = function(tokens, src, filename, tokenizer) {
         prop = expr.list[i]
         val = prop.right
         sem_check_expr(scope, val)
+        if (prop.computed) {
+          sem_check_expr(scope, prop.left)
+        }
         i = i + 1
       }
       return null