[serializer] Add API to warm up startup snapshot with an additional script.

tools/gyp/v8.gyp

Index: tools/gyp/v8.gyp
diff --git a/tools/gyp/v8.gyp b/tools/gyp/v8.gyp
index 0b6609a28f56d5f5b7b70f1cef32b0e6357b841f..4d3334774a7feb8e5c98ed3656b746a82a8676ce 100644
--- a/tools/gyp/v8.gyp
+++ b/tools/gyp/v8.gyp
@@ -31,7 +31,8 @@
     'v8_code': 1,
     'v8_random_seed%': 314159265,
     'v8_vector_stores%': 0,
-    'embed_script%': "",
+    'embed_script%': "-",
+    'warmup_script%': "-",
     'v8_extra_library_files%': [],
     'v8_experimental_extra_library_files%': [],
     'mksnapshot_exec': '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)mksnapshot<(EXECUTABLE_SUFFIX)',
@@ -204,6 +205,7 @@
           'inputs': [
             '<(mksnapshot_exec)',
             '<(embed_script)',
+            '<(warmup_script)',
           ],
           'outputs': [
             '<(INTERMEDIATE_DIR)/snapshot.cc',
@@ -227,6 +229,7 @@
             '<@(mksnapshot_flags)',
             '--startup_src', '<@(INTERMEDIATE_DIR)/snapshot.cc',
             '<(embed_script)',
+            '<(warmup_script)',
           ],
         },
       ],
@@ -330,6 +333,7 @@
                             '<@(mksnapshot_flags_ignition)',
                             '--startup_blob', '<(PRODUCT_DIR)/snapshot_blob_ignition_host.bin',
                             '<(embed_script)',
+                            '<(warmup_script)',
                           ],
                         }, {
                           'outputs': ['<(PRODUCT_DIR)/snapshot_blob_ignition.bin'],
@@ -338,6 +342,7 @@
                             '<@(mksnapshot_flags_ignition)',
                             '--startup_blob', '<(PRODUCT_DIR)/snapshot_blob_ignition.bin',
                             '<(embed_script)',
+                            '<(warmup_script)',
                           ],
                         }],
                       ],
@@ -348,6 +353,7 @@
                         '<@(mksnapshot_flags_ignition)',
                         '--startup_blob', '<(PRODUCT_DIR)/snapshot_blob_ignition.bin',
                         '<(embed_script)',
+                        '<(warmup_script)',
                       ],
                     }],
                   ],
@@ -393,6 +399,7 @@
                         '<@(mksnapshot_flags)',
                         '--startup_blob', '<(PRODUCT_DIR)/snapshot_blob_host.bin',
                         '<(embed_script)',
+                        '<(warmup_script)',
                       ],
                     }, {
                       'outputs': ['<(PRODUCT_DIR)/snapshot_blob.bin'],
@@ -401,6 +408,7 @@
                         '<@(mksnapshot_flags)',
                         '--startup_blob', '<(PRODUCT_DIR)/snapshot_blob.bin',
                         '<(embed_script)',
+                        '<(warmup_script)',
                       ],
                     }],
                   ],
@@ -411,6 +419,7 @@
                     '<@(mksnapshot_flags)',
                     '--startup_blob', '<(PRODUCT_DIR)/snapshot_blob.bin',
                     '<(embed_script)',
+                    '<(warmup_script)',
                   ],
                 }],
               ],