Generate v8_context_snapshot.bin in Static Builds

This file is necessary for builds in which the gn args
v8_use_external_startup_data and use_v8_context_snapshot are both set to true.
There was aprevious  change to include this in the headless component, but it
was only generated for component builds.

The commit sha for the previous change is
8e676c0.

R=alexclarke@chromium.org, skyostil@chromium.org

Bug: 829561
Change-Id: I34a6c8778d6cd7a8b9e635ab48d299163ddea936
Reviewed-on: https://chromium-review.googlesource.com/999013
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Commit-Queue: Sami Kyöstilä <skyostil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561839}

AUTHORS

@@ -267,6 +267,7 @@ Gajendra Singh <wxjg68@motorola.com>
 Ganesh Borle <ganesh.borle@samsung.com>
 Gao Chun <chun.gao@intel.com>
 Gao Chun <gaochun.dev@gmail.com>
+George Adams <geoada@amazon.com>
 George Joseph <kottackal.george@gmail.com>
 George Liaskos <geo.liaskos@gmail.com>
 Georgy Buranov <gburanov@gmail.com>

headless/BUILD.gn

@@ -488,9 +488,11 @@ component("headless") {
         "//components/services/pdf_compositor/public/interfaces",
       ]
     }
+  }
 
-    # Normally set to false (see build/args/headless.gn), but we can optionally
-    # use external v8 startup data too.
+  # Normally set to false (see build/args/headless.gn), but we can optionally
+  # use external v8 startup data too.
+  if ((is_win && is_component_build) || !is_win) {
     if (v8_use_external_startup_data) {
       sources += [ "$root_out_dir/natives_blob.bin" ]
       public_deps += [ "//v8" ]