Fix all dartanalyzer errors in dart:sky except the Native ones.

sky/engine/bindings/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//sky/engine/bindings/bindings.gni")
 import("//sky/engine/core/core.gni")
 
 source_set("bindings") {
   sources = [
     "builtin.cc",
@@ skipping 32 matching lines @@
   ]
   include_dirs = [
     "..",
     "$root_build_dir",
   ]
 }
 
 action("generate_snapshot_bin") {
   deps = [
     "//dart/runtime/bin:gen_snapshot($host_toolchain)",
-    ":generate_sky_core_dart",
+    ":generate_dart_sky",
   ]
   inputs = [
     "//dart/runtime/tools/create_snapshot_bin.py",
     "//sky/engine/bindings/builtin.dart",
     "//mojo/public/dart/bindings.dart",
     "//mojo/public/dart/core.dart",
     "//mojo/public/dart/src/application.dart",
     "//mojo/public/dart/src/application_connection.dart",
     "//mojo/public/dart/src/buffer.dart",
     "//mojo/public/dart/src/codec.dart",
@@ skipping 10 matching lines @@
     "//mojo/public/dart/src/timer_queue.dart",
     "//mojo/public/dart/src/types.dart",
     "snapshot.dart",
   ]
   output = "$target_gen_dir/snapshot_gen.bin"
   outputs = [
     output,
   ]
 
   builtin_path = rebase_path("//sky/engine/bindings/builtin.dart")
-  sky_core_path = rebase_path("$bindings_output_dir/sky_core.dart")
+  dart_sky_path = rebase_path("$bindings_output_dir/dart_sky.dart")
   mojo_bindings_path = rebase_path("//mojo/public/dart/bindings.dart")
   mojo_core_path = rebase_path("//mojo/public/dart/core.dart")
 
   gen_snapshot_dir =
       get_label_info("//dart/runtime/bin:gen_snapshot($host_toolchain)",
                      "root_out_dir")
   script = "//dart/runtime/tools/create_snapshot_bin.py"
 
   args = [
     "--executable",
     rebase_path("$gen_snapshot_dir/gen_snapshot"),
     "--package_root",
     rebase_path("$root_gen_dir"),
     "--script",
     rebase_path("snapshot.dart"),
     "--output_bin",
     rebase_path(output, root_build_dir),
     "--target_os",
     os,
-    "--url_mapping=dart:sky,$sky_core_path",
+    "--url_mapping=dart:sky,$dart_sky_path",
     "--url_mapping=mojo:bindings,$mojo_bindings_path",
     "--url_mapping=mojo:core,$mojo_core_path",
     "--url_mapping=dart:sky_builtin,$builtin_path",
   ]
 }
 
 action("generate_snapshot_file") {
   deps = [
     ":generate_snapshot_bin",
   ]
@@ skipping 212 matching lines @@
     "--generate-globals",
     rebase_path(bindings_output_dir, root_build_dir),
     rebase_path(file_list, root_build_dir),
   ]
 
   deps = [
     ":compile_idls",
   ]
 }
 
-action("generate_sky_core_dart") {
+action("generate_dart_sky") {
   sources = core_idl_files
   script = "$bindings_scripts_dir/compiler.py"
 
   file_list = "$target_gen_dir/${target_name}_file_list.txt"
   write_file(file_list, rebase_path(sources, root_build_dir))
 
   inputs =
       sources + idl_compiler_files + [ "scripts/templates/dart_blink.template" ]
 
   outputs = [
     file_list,
-    "$bindings_output_dir/sky_core.dart",
+    "$bindings_output_dir/dart_sky.dart",
   ]
 
   args = [
     "--output-directory",
     rebase_path(bindings_output_dir, root_build_dir),
     "--generate-dart-blink",
     rebase_path(bindings_output_dir, root_build_dir),
     rebase_path(file_list, root_build_dir),
   ]
 
@@ skipping 30 matching lines @@
   ]
 
   include_dirs = [
     "..",
     "$root_build_dir",
   ]
 
   sources = get_target_outputs(":compile_idls")
   sources += get_target_outputs(":generate_dart_globals")
 }