[build] Link V8 as component in static library builds

BUG=v8:5435
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_chromium_compile_dbg_ng;master.tryserver.chromium.android:android_clang_dbg_recipe

Review-Url: https://codereview.chromium.org/2373783002
Cr-Commit-Position: refs/heads/master@{#41304}

BUILD.gn

@@ -2516,6 +2516,7 @@ if (is_component_build) {
       ":v8_base",
       ":v8_maybe_snapshot",
     ]
+
     public_configs = [ ":external_config" ]
   }
 }

build_overrides/v8.gni

@@ -18,3 +18,8 @@ v8_experimental_extra_library_files =
     [ "//test/cctest/test-experimental-extra.js" ]
 
 v8_enable_inspector_override = true
+
+declare_args() {
+  # Use static libraries instead of source_sets.
+  v8_static_library = false
+}

gni/v8.gni

@@ -87,11 +87,20 @@ if (is_posix && v8_enable_backtrace) {
 
 # All templates should be kept in sync.
 template("v8_source_set") {
-  source_set(target_name) {
-    forward_variables_from(invoker, "*", [ "configs" ])
-    configs += invoker.configs
-    configs -= v8_remove_configs
-    configs += v8_add_configs
+  if (defined(v8_static_library) && v8_static_library) {
+    static_library(target_name) {
+      forward_variables_from(invoker, "*", [ "configs" ])
+      configs += invoker.configs
+      configs -= v8_remove_configs
+      configs += v8_add_configs
+    }
+  } else {
+    source_set(target_name) {
+      forward_variables_from(invoker, "*", [ "configs" ])
+      configs += invoker.configs
+      configs -= v8_remove_configs
+      configs += v8_add_configs
+    }
   }
 }