Handle dynamic as bottom inside of function type reps

test/codegen/expect/constructors.js

 dart_library.library('constructors', null, /* Imports */[
   "dart_runtime/dart",
   'dart/core'
 ], /* Lazy imports */[
 ], function(exports, dart, core) {
   'use strict';
   let dartx = dart.dartx;
   class A extends core.Object {}
   class B extends core.Object {
     B() {
@@ skipping 103 matching lines @@
       K: [K, []],
       withS: [K, [core.String]]
     })
   });
   class L extends core.Object {
     L(foo) {
       this.foo = foo;
     }
   }
   dart.setSignature(L, {
-    constructors: () => ({L: [L, [core.Object]]})
+    constructors: () => ({L: [L, [dart.dynamic]]})
   });
   class M extends L {
     named(x) {
       super.L(dart.notNull(x) + 42);
     }
   }
   dart.defineNamedConstructor(M, 'named');
   dart.setSignature(M, {
     constructors: () => ({named: [M, [core.int]]})
   });
@@ skipping 41 matching lines @@
       bar2() {
         let q = new (Q$())("world");
         return dart.as(q.x, core.String);
       }
       static baz() {
         let q = new (Q$(core.int))(42);
         return dart.notNull(q.bar()) + dart.notNull(q.bar2());
       }
     }
     dart.setSignature(Q, {
-      constructors: () => ({Q: [Q$(T), [core.Object]]}),
+      constructors: () => ({Q: [Q$(T), [dart.dynamic]]}),
       methods: () => ({
         bar: [core.String, []],
         bar2: [core.String, []]
       }),
       statics: () => ({
         foo: [Q$(), []],
         baz: [core.String, []]
       }),
       names: ['foo', 'baz']
     });
@@ skipping 13 matching lines @@
   exports.I = I;
   exports.J = J;
   exports.K = K;
   exports.L = L;
   exports.M = M;
   exports.N = N;
   exports.P = P;
   exports.Q$ = Q$;
   exports.Q = Q;
 });