Reland "Turn libbase into a component"

test/unittests/BUILD.gn

 # Copyright 2016 The V8 project 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("../../gni/v8.gni")
 
 v8_executable("unittests") {
   testonly = true
 
   sources = [
@@ skipping 141 matching lines @@
     "../..:external_config",
     "../..:internal_config_base",
   ]
 
   # TODO(machenbach): Translate from gyp.
   #['OS=="aix"', {
   #  'ldflags': [ '-Wl,-bbigtoc' ],
   #}],
 
   deps = [
+    "../..:v8_libbase",
     "../..:v8_libplatform",
     "//build/config/sanitizers:deps",
     "//build/win:default_exe_manifest",
     "//testing/gmock",
     "//testing/gtest",
   ]
 
   if (is_component_build) {
     # compiler-unittests can't be built against a shared library, so we
     # need to depend on the underlying static target in that case.
@@ skipping 10 matching lines @@
 
     # Suppress warnings about importing locally defined symbols.
     if (is_component_build) {
       ldflags = [
         "/ignore:4049",
         "/ignore:4217",
       ]
     }
   }
 }