Reland of move v8_toolset_for_d8 flag

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 38ac768786476006948521a1c3943bb126db2f8b..6f1aaaff02c6a71a7b884bf182d7f928baaca703 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -64,7 +64,6 @@
 }
 
 v8_random_seed = "314159265"
-v8_toolset_for_d8 = "host"
 v8_toolset_for_shell = "host"
 
 if (is_msan) {
@@ -2066,13 +2065,51 @@
   }
 }
 
-if ((current_toolchain == host_toolchain && v8_toolset_for_d8 == "host") ||
-    (current_toolchain == snapshot_toolchain && v8_toolset_for_d8 == "host") ||
-    (current_toolchain != host_toolchain && v8_toolset_for_d8 == "target")) {
-  executable("d8") {
+executable("d8") {
+  sources = [
+    "src/d8.cc",
+    "src/d8.h",
+  ]
+
+  configs -= [ "//build/config/compiler:chromium_code" ]
+  configs += [ "//build/config/compiler:no_chromium_code" ]
+  configs += [
+    # Note: don't use :internal_config here because this target will get
+    # the :external_config applied to it by virtue of depending on :v8, and
+    # you can't have both applied to the same target.
+    ":internal_config_base",
+    ":features",
+    ":toolchain",
+  ]
+
+  deps = [
+    ":d8_js2c",
+    ":v8",
+    ":v8_libplatform",
+    "//build/config/sanitizers:deps",
+    "//build/win:default_exe_manifest",
+  ]
+
+  # TODO(jochen): Add support for vtunejit.
+
+  if (is_posix) {
+    sources += [ "src/d8-posix.cc" ]
+  } else if (is_win) {
+    sources += [ "src/d8-windows.cc" ]
+  }
+
+  if (!is_component_build) {
+    sources += [ "$target_gen_dir/d8-js.cc" ]
+  }
+  if (v8_enable_i18n_support) {
+    deps += [ "//third_party/icu" ]
+  }
+}
+
+if ((current_toolchain == host_toolchain && v8_toolset_for_shell == "host") || (current_toolchain == snapshot_toolchain && v8_toolset_for_shell == "host") || (current_toolchain != host_toolchain && v8_toolset_for_shell == "target")) {
+  executable("v8_shell") {
     sources = [
-      "src/d8.cc",
-      "src/d8.h",
+      "samples/shell.cc",
     ]
 
     configs -= [ "//build/config/compiler:chromium_code" ]
@@ -2087,60 +2124,18 @@
     ]
 
     deps = [
-      ":d8_js2c",
       ":v8",
       ":v8_libplatform",
       "//build/config/sanitizers:deps",
       "//build/win:default_exe_manifest",
     ]
 
-    # TODO(jochen): Add support for vtunejit.
-
-    if (is_posix) {
-      sources += [ "src/d8-posix.cc" ]
-    } else if (is_win) {
-      sources += [ "src/d8-windows.cc" ]
-    }
-
-    if (!is_component_build) {
-      sources += [ "$target_gen_dir/d8-js.cc" ]
-    }
     if (v8_enable_i18n_support) {
       deps += [ "//third_party/icu" ]
     }
   }
 }
 
-if ((current_toolchain == host_toolchain && v8_toolset_for_shell == "host") || (current_toolchain == snapshot_toolchain && v8_toolset_for_shell == "host") || (current_toolchain != host_toolchain && v8_toolset_for_shell == "target")) {
-  executable("v8_shell") {
-    sources = [
-      "samples/shell.cc",
-    ]
-
-    configs -= [ "//build/config/compiler:chromium_code" ]
-    configs += [ "//build/config/compiler:no_chromium_code" ]
-    configs += [
-      # Note: don't use :internal_config here because this target will get
-      # the :external_config applied to it by virtue of depending on :v8, and
-      # you can't have both applied to the same target.
-      ":internal_config_base",
-      ":features",
-      ":toolchain",
-    ]
-
-    deps = [
-      ":v8",
-      ":v8_libplatform",
-      "//build/config/sanitizers:deps",
-      "//build/win:default_exe_manifest",
-    ]
-
-    if (v8_enable_i18n_support) {
-      deps += [ "//third_party/icu" ]
-    }
-  }
-}
-
 v8_source_set("json_fuzzer") {
   sources = [
     "test/fuzzer/json.cc",