[Memory Sheriff] Widen FileStream suppression.

tools/heapcheck/suppressions.txt

 # There are three kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 847 matching lines @@
 {
    bug_250533
    Heapcheck:Leak
    ...
    fun:net::TestURLRequestContextGetter::GetURLRequestContext
    fun:ProxyResolvingClientSocket
    fun:jingle_glue::XmppClientSocketFactory::CreateTransportClientSocket
    fun:jingle_glue::ChromeAsyncSocket::Connect
 }
 {
+   bug_251004
+   Heapcheck:Leak
+   fun:base::internal::PostTaskAndReplyImpl::PostTaskAndReply
+   fun:base::TaskRunner::PostTaskAndReply
+   fun:net::FileStream::Context::CloseAndDelete
+   fun:net::FileStream::Context::Orphan
+}
+{
    bug_251034_a
    Heapcheck:Leak
    ...
    fun:gfx::OSMESAApiBase::OSMesaMakeCurrentFn
    fun:gfx::GLContextOSMesa::MakeCurrent
    fun:gpu::gles2::GLES2DecoderImpl::MakeCurrent
    fun:webkit::gpu::GLInProcessContext::PumpCommands
 }
 {
    bug_251034_b
@@ skipping 34 matching lines @@
    fun:gfx::OSMESAApiBase::OSMesaMakeCurrentFn
    fun:gfx::GLContextOSMesa::MakeCurrent
    fun:~ScopedMakeCurrent
    fun:base::DefaultDeleter::operator
    fun:~scoped_ptr_impl
    fun:~scoped_ptr
    fun:gfx::GLSurfaceOSMesa::Resize
    fun:gfx::NativeViewGLSurfaceOSMesa::Resize
    fun:webkit::gpu::GLInProcessContext::OnResizeView
 }