[Compiler] If bytecode is flushed during code deserialization, fall through to recompile.

With stress bytecode flushing it's possible for the main SFI of a script to have it's
bytecode flushed during deserialization of the script. If this happens, just fall-through
to recompile the SFI.

BUG=v8:8901,v8:8395

Change-Id: I786c1ca93167b76810481892ade525d14ff9168f
Reviewed-on: https://chromium-review.googlesource.com/c/1485837Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59831}

src/compiler.cc

@@ -1847,7 +1847,8 @@ MaybeHandle<SharedFunctionInfo> Compiler::GetSharedFunctionInfoForScript(
       Handle<SharedFunctionInfo> inner_result;
       if (CodeSerializer::Deserialize(isolate, cached_data, source,
                                       origin_options)
-              .ToHandle(&inner_result)) {
+              .ToHandle(&inner_result) &&
+          inner_result->is_compiled()) {
         // Promote to per-isolate compilation cache.
         is_compiled_scope = inner_result->is_compiled_scope();
         DCHECK(is_compiled_scope.is_compiled());