[tools] Remove unused V8 dependency on Fuchsia's "launchpad" package.

R=sergiyb@chromium.org

Bug: chromium:848028
Change-Id: If8ce38ff0e991e171eae68e2bea708365e63a35c
Reviewed-on: https://chromium-review.googlesource.com/1099601
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53719}

BUILD.gn

@@ -2961,7 +2961,6 @@ v8_component("v8_libbase") {
       "src/base/debug/stack_trace_fuchsia.cc",
       "src/base/platform/platform-fuchsia.cc",
     ]
-    public_deps += [ "//third_party/fuchsia-sdk:launchpad" ]
   } else if (is_mac) {
     sources += [
       "src/base/debug/stack_trace_posix.cc",