[incremental] Fix unbound template variable

This reverts commit 1a307252.

fixes #332

src/jastadd/ast/JragCodeGen.jrag

@@ -631,10 +631,12 @@ aspect JragCodeGen {
    * Generates the Java method to evaluate an attribute.
    */
   public void AttrDecl.emitAttrEquation(PrintStream out) {
+    TemplateContext tc = templateContext();
+    tc.bind("HostClass", hostClassName());
     if (isCircular()) {
-      templateContext().bind("CircularComputeRhs", circularComputeRhs());
+      tc.bind("CircularComputeRhs", circularComputeRhs());
     } else {
-      templateContext().bind("ComputeRhs", computeRhs());
+      tc.bind("ComputeRhs", computeRhs());
     }
     emitAttrEquationWithComment(out, parametersDecl(), docComment());
   }

src/template/incremental/Notification.tt

@@ -235,7 +235,7 @@ $endif
   #resetCache
   #(signature)_handler.notifyDependencies();
   $if (TraceFlush)
-  state().trace().flushIncAttr(#hostClassName.this, "#hostClassName.#signatureJavaStyle", "", "");
+  state().trace().flushIncAttr($HostClass.this, "#signature", "", "");
   $endif
 }
 $endif