Introduce element categories and move resolver towards being more compositional.

dart/frog/leg/ssa/builder.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class Interceptors {
   Compiler compiler;
   Interceptors(Compiler this.compiler);
 
   SourceString mapOperatorToMethodName(Operator op) {
     String name = op.source.stringValue;
@@ skipping 1763 matching lines @@
         native.handleSsaNative(this, node);
         break;
       default:
         throw "Unknown foreign: ${node.selector}";
     }
   }
 
   visitSuperSend(Send node) {
     Selector selector = elements.getSelector(node);
     Element element = elements[node];
+    if (element.kind.category != ElementCategory.FUNCTION) {
+      // Example:
+      // co19/Language/10_Expressions/14_Method_Invocation/3_Super_Invocation_A03_t04
+      compiler.unimplemented('super-send to non-function', node: node);
+    }
     HStatic target = new HStatic(element);
     HInstruction context = localsHandler.readThis();
     add(target);
     var inputs = <HInstruction>[target, context];
     addStaticSendArgumentsToList(node, element, inputs);
     push(new HInvokeSuper(selector, inputs));
   }
 
   visitStaticSend(Send node) {
     Selector selector = elements.getSelector(node);
@@ skipping 272 matching lines @@
         new HIfBlockInformation(condition, thenGraph, elseGraph, joinBlock);
     open(joinBlock);
 
     localsHandler.mergeWith(thenLocals, joinBlock);
     HPhi phi = new HPhi.manyInputs(null, [thenInstruction, elseInstruction]);
     joinBlock.addPhi(phi);
     stack.add(phi);
   }
 
   visitStringInterpolation(StringInterpolation node) {
-    Operator op = new Operator.synthetic("+");
+    int offset = node.getBeginToken().charOffset;
+    Operator op = new Operator(new StringToken(PLUS_INFO, "+", offset));
     HInstruction target = new HStatic(interceptors.getOperatorInterceptor(op));
     add(target);
     visit(node.string);
     // Handle the parts here, to avoid recreating [target].
     for (StringInterpolationPart part in node.parts) {
       HInstruction prefix = pop();
       visit(part.expression);
       push(new HAdd(target, prefix, pop()));
       prefix = pop();
       visit(part.string);
@@ skipping 390 matching lines @@
     // Normally, we would call [close] here. However, then we hit
     // another unimplemented feature: aborting loop body. Simply
     // calling [add] does not work as it asserts that the instruction
     // isn't a control flow instruction. So we inline parts of [add].
     current.addAfter(current.last, new HThrow(message));
     if (isExpression) {
       stack.add(graph.addConstantNull());
     }
   }
 }