changing extends to composes and everything is passing!

Author: geelen

test/test-cases/multiple-dependencies/b.css

@@ -1,4 +1,4 @@
 .b {
-  extends: d from "./d.css";
+  composes: d from "./d.css";
   color: #bbb;
 }

test/test-cases/multiple-dependencies/source.css

@@ -1,6 +1,6 @@
 .a {
-  extends: b from "./b.css";
-  extends: c from "./c.css";
+  composes: b from "./b.css";
+  composes: c from "./c.css";
   color: #aaa;
 }
 

test/test-cases/single-import-export/source.css

@@ -1,4 +1,4 @@
 .localName {
-  extends: blackShadow from "./colors.css";
+  composes: blackShadow from "./colors.css";
   color: red;
 }