[test] Move CodeAssembler tests to a separate file.

test/cctest/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.
 
 # Please keep this file in sync with cctest.gyp.
 
 import("../../gni/v8.gni")
 
 v8_executable("cctest") {
   testonly = true
 
   sources = [
     "$target_gen_dir/resources.cc",
     "cctest.cc",
     "compiler/c-signature.h",
+    "compiler/code-assembler-tester.h",
     "compiler/codegen-tester.cc",
     "compiler/codegen-tester.h",
     "compiler/function-tester.h",
     "compiler/graph-builder-tester.h",
     "compiler/test-basic-block-profiler.cc",
     "compiler/test-branch-combine.cc",
+    "compiler/test-code-assembler.cc",
     "compiler/test-gap-resolver.cc",
     "compiler/test-graph-visualizer.cc",
     "compiler/test-instruction.cc",
     "compiler/test-js-constant-cache.cc",
     "compiler/test-js-context-specialization.cc",
     "compiler/test-js-typed-lowering.cc",
     "compiler/test-jump-threading.cc",
     "compiler/test-linkage.cc",
     "compiler/test-loop-analysis.cc",
     "compiler/test-loop-assignment-analysis.cc",
@@ skipping 329 matching lines @@
     "$target_gen_dir/resources.cc",
   ]
 
   args = [
     rebase_path("$target_gen_dir/resources.cc", root_build_dir),
     "TEST",
   ]
   args += rebase_path(sources, root_build_dir)
 }
 # TODO(machenbach): Migrate generate-bytecode-expectations.