Add DartType.treatAsRaw to treat List<dynamic> as List in the backend.

sdk/lib/_internal/compiler/implementation/ssa/optimize.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.
 
 part of ssa;
 
 abstract class OptimizationPhase {
   String get name;
   void visitGraph(HGraph graph);
 }
@@ skipping 633 matching lines @@
         return graph.addConstantBool(false, compiler);
       }
     }
     return node;
   }
 
   HInstruction visitTypeConversion(HTypeConversion node) {
     HInstruction value = node.inputs[0];
     DartType type = node.typeExpression;
     if (type != null) {
-      if (!type.isRaw || type.kind == TypeKind.TYPE_VARIABLE) {
+      if (!type.treatAsRaw || type.kind == TypeKind.TYPE_VARIABLE) {
         return node;
       }
       if (type.kind == TypeKind.FUNCTION) {
         // TODO(johnniwinther): Optimize function type conversions.
         return node;
       }
     }
     HType convertedType = node.instructionType;
     if (convertedType.isUnknown()) return node;
     HType combinedType = value.instructionType.intersection(
@@ skipping 97 matching lines @@
 
     HInstruction receiver = node.getDartReceiver(compiler);
     Element field = findConcreteFieldForDynamicAccess(receiver, node.selector);
     if (field == null || !field.isAssignable()) return node;
     // Use [:node.inputs.last:] in case the call follows the
     // interceptor calling convention, but is not a call on an
     // interceptor.
     HInstruction value = node.inputs.last;
     if (compiler.enableTypeAssertions) {
       DartType type = field.computeType(compiler);
-      if (!type.isRaw || type.kind == TypeKind.TYPE_VARIABLE) {
+      if (!type.treatAsRaw || type.kind == TypeKind.TYPE_VARIABLE) {
         // We cannot generate the correct type representation here, so don't
         // inline this access.
         return node;
       }
       HInstruction other = value.convertType(
           compiler,
           type,
           HTypeConversion.CHECKED_MODE_CHECK);
       if (other != value) {
         node.block.addBefore(node, other);
@@ skipping 768 matching lines @@
       // that knows it is not of a specific Type.
     }
 
     for (HIf ifUser in notIfUsers) {
       changeUsesDominatedBy(ifUser.elseBlock, input, convertedType);
       // TODO(ngeoffray): Also change uses for the then block on a HType
       // that knows it is not of a specific Type.
     }
   }
 }