Revert of Remove v8_toolset_for_d8 flag (patchset #1 id:1 of...

Revert of Remove v8_toolset_for_d8 flag (patchset #1 id:1 of https://codereview.chromium.org/1969793002/ )

Reason for revert:
blocks roll: https://codereview.chromium.org/1975753002/

Original issue's description:
> Remove v8_toolset_for_d8 flag
>
> R=machenbach@chromium.org
> BUG=chromium:609107
>
> Committed: https://crrev.com/6cb38427984f3c31ff6c8813535cfd6ebf6058c4
> Cr-Commit-Position: refs/heads/master@{#36198}

TBR=machenbach@chromium.org,jochen@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:609107

Review-Url: https://codereview.chromium.org/1974773002
Cr-Commit-Position: refs/heads/master@{#36209}

BUILD.gn

@@ -64,6 +64,7 @@ declare_args() {
 }
 
 v8_random_seed = "314159265"
+v8_toolset_for_d8 = "host"
 v8_toolset_for_shell = "host"
 
 if (is_msan) {
@@ -2065,7 +2066,10 @@ if (is_component_build) {
   }
 }
 
-executable("d8") {
+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") {
     sources = [
       "src/d8.cc",
       "src/d8.h",
@@ -2104,6 +2108,7 @@ executable("d8") {
     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")) {

gypfiles/toolchain.gypi

@@ -76,6 +76,11 @@
     # it's handled in gypfiles/standalone.gypi.
     'want_separate_host_toolset%': 1,
 
+    # Toolset the d8 binary should be compiled for. Possible values are 'host'
+    # and 'target'. If you want to run v8 tests, it needs to be set to 'target'.
+    # The setting is ignored if want_separate_host_toolset is 0.
+    'v8_toolset_for_d8%': 'target',
+
     # Toolset the shell binary should be compiled for. Possible values are
     # 'host' and 'target'.
     # The setting is ignored if want_separate_host_toolset is 0.

src/d8.gyp

@@ -31,6 +31,7 @@
     # Enable support for Intel VTune. Supported on ia32/x64 only
     'v8_enable_vtunejit%': 0,
     'v8_enable_i18n_support%': 1,
+    'v8_toolset_for_d8%': 'target',
   },
   'includes': ['../gypfiles/toolchain.gypi', '../gypfiles/features.gypi'],
   'targets': [
@@ -51,7 +52,7 @@
       ],
       'conditions': [
         [ 'want_separate_host_toolset==1', {
-          'toolsets': [ 'target', ],
+          'toolsets': [ '<(v8_toolset_for_d8)', ],
         }],
         ['(OS=="linux" or OS=="mac" or OS=="freebsd" or OS=="netbsd" \
            or OS=="openbsd" or OS=="solaris" or OS=="android" \
@@ -140,7 +141,7 @@
     },
   ],
   'conditions': [
-    ['test_isolation_mode != "noop"', {
+    ['test_isolation_mode != "noop" and v8_toolset_for_d8 == "target"', {
       'targets': [
         {
           'target_name': 'd8_run',