[gn] Add v8_monolith static library target.

R=machenbach@chromium.org

Bug: v8:6105
Change-Id: I51d7d38897d1b20469304345d11228a8f78d3489
Reviewed-on: https://chromium-review.googlesource.com/788376
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49627}

BUILD.gn

@@ -132,6 +132,8 @@ declare_args() {
   # Temporary flag to allow embedders to update their microtasks scopes
   # while rolling in a new version of V8.
   v8_check_microtasks_scopes_consistency = ""
+
+  v8_monolithic = false
 }
 
 # Derived defaults.
@@ -2680,6 +2682,30 @@ v8_source_set("fuzzer_support") {
   ]
 }
 
+###############################################################################
+# Produce a single static library for embedders
+#
+
+if (v8_monolithic) {
+  # A component build is not monolithic.
+  assert(!is_component_build)
+
+  # Using external startup data would produce separate files.
+  assert(!v8_use_external_startup_data)
+  v8_static_library("v8_monolith") {
+    deps = [
+      ":v8",
+      ":v8_libbase",
+      ":v8_libplatform",
+      ":v8_libsampler",
+      "//build/config:exe_and_shlib_deps",
+      "//build/win:default_exe_manifest",
+    ]
+
+    configs = [ ":internal_config" ]
+  }
+}
+
 ###############################################################################
 # Executables
 #

gni/v8.gni

@@ -174,3 +174,13 @@ template("v8_component") {
     configs += v8_add_configs
   }
 }
+
+template("v8_static_library") {
+  static_library(target_name) {
+    complete_static_lib = true
+    forward_variables_from(invoker, "*", [ "configs" ])
+    configs += invoker.configs
+    configs -= v8_remove_configs
+    configs += v8_add_configs
+  }
+}