Introduce _emitParameterReferences to avoid mixing params with param references.

test/codegen/expect/destructuring.js

 dart_library.library('destructuring', null, /* Imports */[
   'dart/_runtime',
   'dart/core'
 ], /* Lazy imports */[
 ], function(exports, dart, core) {
   'use strict';
   let dartx = dart.dartx;
   function f(a, b, c = 1) {
     f(a, b, c);
   }
   dart.fn(f, dart.dynamic, [core.int, dart.dynamic], [dart.dynamic]);
+  function f_sync(a, b, c = 1) {
+    return dart.syncStar(function*(a, b, c = 1) {
+    }, dart.dynamic, a, b, c);
+  }
+  dart.fn(f_sync, dart.dynamic, [core.int, dart.dynamic], [dart.dynamic]);
+  function f_async(a, b, c = 1) {
+    return dart.asyncStar(function*(stream, a, b, c = 1) {
+    }, dart.dynamic, a, b, c);
+  }
+  dart.fn(f_async, dart.dynamic, [core.int, dart.dynamic], [dart.dynamic]);
   function g(a, b, {c = 1} = {}) {
     f(a, b, c);
   }
   dart.fn(g, dart.dynamic, [core.int, dart.dynamic], {c: dart.dynamic});
+  function g_sync(a, b, {c = 1} = {}) {
+    return dart.syncStar(function*(a, b, {c = 1} = {}) {
+    }, dart.dynamic, a, b, opts);
+  }
+  dart.fn(g_sync, dart.dynamic, [core.int, dart.dynamic], {c: dart.dynamic});
+  function g_async(a, b, {c = 1} = {}) {
+    return dart.asyncStar(function*(stream, a, b, {c = 1} = {}) {
+    }, dart.dynamic, a, b, opts);
+  }
+  dart.fn(g_async, dart.dynamic, [core.int, dart.dynamic], {c: dart.dynamic});
+  function r(a, ...others) {
+    r(a, ...others);
+  }
+  dart.fn(r, dart.dynamic, [core.int, dart.dynamic]);
+  function r_sync(a, ...others) {
+    return dart.syncStar(function*(a, ...others) {
+    }, dart.dynamic, a, ...others);
+  }
+  dart.fn(r_sync, dart.dynamic, [core.int, dart.dynamic]);
+  function r_async(a, ...others) {
+    return dart.asyncStar(function*(stream, a, ...others) {
+    }, dart.dynamic, a, ...others);
+  }
+  dart.fn(r_async, dart.dynamic, [core.int, dart.dynamic]);
   function invalid_names1(let$, func, arguments$) {
     f(let$, func, arguments$);
   }
   dart.fn(invalid_names1, dart.dynamic, [core.int, dart.dynamic, dart.dynamic]);
   function invalid_names2(let$ = null, func = 1, arguments$ = null) {
     f(let$, func, arguments$);
   }
   dart.fn(invalid_names2, dart.dynamic, [], [core.int, dart.dynamic, dart.dynamic]);
   function invalid_names3({["let"]: let$ = null, ["function"]: func = null, ["arguments"]: arguments$ = 2} = {}) {
     f(let$, func, arguments$);
   }
   dart.fn(invalid_names3, dart.dynamic, [], {let: core.int, function: dart.dynamic, arguments: dart.dynamic});
   function names_clashing_with_object_props({constructor = null, valueOf = null, hasOwnProperty = 2} = Object.create(null)) {
     f(constructor, valueOf, hasOwnProperty);
   }
   dart.fn(names_clashing_with_object_props, dart.dynamic, [], {constructor: core.int, valueOf: dart.dynamic, hasOwnProperty: dart.dynamic});
   // Exports:
   exports.f = f;
+  exports.f_sync = f_sync;
+  exports.f_async = f_async;
   exports.g = g;
+  exports.g_sync = g_sync;
+  exports.g_async = g_async;
+  exports.r = r;
+  exports.r_sync = r_sync;
+  exports.r_async = r_async;
   exports.invalid_names1 = invalid_names1;
   exports.invalid_names2 = invalid_names2;
   exports.invalid_names3 = invalid_names3;
   exports.names_clashing_with_object_props = names_clashing_with_object_props;
 });