[wasm] Rename ast-decoder.* to function-body-decoder.*

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 112 matching lines @@
     "locked-queue-unittest.cc",
     "object-unittest.cc",
     "register-configuration-unittest.cc",
     "run-all-unittests.cc",
     "source-position-table-unittest.cc",
     "test-utils.cc",
     "test-utils.h",
     "unicode-unittest.cc",
     "value-serializer-unittest.cc",
     "wasm/asm-types-unittest.cc",
-    "wasm/ast-decoder-unittest.cc",
     "wasm/control-transfer-unittest.cc",
     "wasm/decoder-unittest.cc",
+    "wasm/function-body-decoder-unittest.cc",
     "wasm/leb-helper-unittest.cc",
     "wasm/loop-assignment-analysis-unittest.cc",
     "wasm/module-decoder-unittest.cc",
     "wasm/switch-logic-unittest.cc",
     "wasm/wasm-macro-gen-unittest.cc",
     "wasm/wasm-module-builder-unittest.cc",
     "zone/segmentpool-unittest.cc",
     "zone/zone-chunk-list-unittest.cc",
   ]
 
@@ skipping 39 matching lines @@
     deps += [ "//third_party/icu" ]
   }
 
   if (is_win) {
     # This warning is benignly triggered by the U16 and U32 macros in
     # bytecode-utils.h.
     # C4309: 'static_cast': truncation of constant value
     cflags = [ "/wd4309" ]
   }
 }