Make GYP build usable for day-to-day work

src/d8.gyp

Index: src/d8.gyp
diff --git a/src/d8.gyp b/src/d8.gyp
index d2b42540388ea9133a1ccaa75274e2954876841e..cece778d247bb174c35bc4b8e4c7bfa22ca06b28 100644
--- a/src/d8.gyp
+++ b/src/d8.gyp
@@ -47,15 +47,24 @@
       ],
       'conditions': [
         [ 'component!="shared_library"', {
-          'dependencies': [ 'd8_js2c#host', ], 
           'sources': [ 'd8-debug.cc', '<(SHARED_INTERMEDIATE_DIR)/d8-js.cc', ],
           'conditions': [
+            [ 'want_separate_host_toolset==1', {
+              'dependencies': [
+                'd8_js2c#host',
+              ],
+            }, {
+              'dependencies': [
+                'd8_js2c',
+              ],
+            }],
             [ 'console=="readline"', {
               'libraries': [ '-lreadline', ],
               'sources': [ 'd8-readline.cc' ],
             }],
             [ '(OS=="linux" or OS=="mac" or OS=="freebsd" \
               or OS=="openbsd" or OS=="solaris")', {
+              'cflags!': [ '-pedantic' ],
               'sources': [ 'd8-posix.cc', ]
             }],
             [ 'OS=="win"', {
@@ -68,13 +77,19 @@
     {
       'target_name': 'd8_js2c',
       'type': 'none',
-      'toolsets': ['host'],
       'variables': {
         'js_files': [
           'd8.js',
           'macros.py',
         ],
       },
+      'conditions': [
+        [ 'want_separate_host_toolset==1', {
+          'toolsets': ['host'],
+        }, {
+          'toolsets': ['target'],
+        }]
+      ],
       'actions': [
         {
           'action_name': 'd8_js2c',