Remove wasm compile time option and enable wasm behind a runtime flag.

BUILD.gn

 # Copyright 2014 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("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 if (is_android) {
@@ skipping 849 matching lines @@
     "src/compiler/type-hint-analyzer.cc",
     "src/compiler/type-hint-analyzer.h",
     "src/compiler/type-hints.cc",
     "src/compiler/type-hints.h",
     "src/compiler/typer.cc",
     "src/compiler/typer.h",
     "src/compiler/value-numbering-reducer.cc",
     "src/compiler/value-numbering-reducer.h",
     "src/compiler/verifier.cc",
     "src/compiler/verifier.h",
+    "src/compiler/wasm-compiler.cc",
+    "src/compiler/wasm-compiler.h",
+    "src/compiler/wasm-linkage.cc",
     "src/compiler/zone-pool.cc",
     "src/compiler/zone-pool.h",
     "src/compiler.cc",
     "src/compiler.h",
     "src/context-measure.cc",
     "src/context-measure.h",
     "src/contexts-inl.h",
     "src/contexts.cc",
     "src/contexts.h",
     "src/conversions-inl.h",
@@ skipping 395 matching lines @@
     "src/utils.h",
     "src/v8.cc",
     "src/v8.h",
     "src/v8memory.h",
     "src/v8threads.cc",
     "src/v8threads.h",
     "src/version.cc",
     "src/version.h",
     "src/vm-state-inl.h",
     "src/vm-state.h",
+    "src/wasm/asm-wasm-builder.cc",
+    "src/wasm/asm-wasm-builder.h",
+    "src/wasm/ast-decoder.cc",
+    "src/wasm/ast-decoder.h",
+    "src/wasm/decoder.h",
+    "src/wasm/encoder.cc",
+    "src/wasm/encoder.h",
+    "src/wasm/module-decoder.cc",
+    "src/wasm/module-decoder.h",
+    "src/wasm/wasm-js.cc",
+    "src/wasm/wasm-js.h",
+    "src/wasm/wasm-macro-gen.h",
+    "src/wasm/wasm-module.cc",
+    "src/wasm/wasm-module.h",
+    "src/wasm/wasm-opcodes.cc",
+    "src/wasm/wasm-opcodes.h",
+    "src/wasm/wasm-result.cc",
+    "src/wasm/wasm-result.h",
     "src/zone.cc",
     "src/zone.h",
     "src/zone-allocator.h",
     "src/zone-containers.h",
     "src/third_party/fdlibm/fdlibm.cc",
     "src/third_party/fdlibm/fdlibm.h",
   ]
 
   if (v8_target_arch == "x86") {
     sources += [
@@ skipping 556 matching lines @@
     if (!is_component_build) {
       sources += [
         "$target_gen_dir/d8-js.cc",
       ]
     }
     if (v8_enable_i18n_support) {
       deps += [ "//third_party/icu" ]
     }
   }
 }