[Compile] Remove unecessary class_function_descriptors access.

BuildClassBoilerplate accessed the native context to get the
class_function_descriptors. Baseline compilation should be native context
independent, so we shouldn't access the native context at all. As it happens,
class_function_descriptors wasn't used so can just be removed.

BUG=chromium:898076, v8:8041

Change-Id: If9c0edf3dfde68c76ea87820f9d4b080aac6d60e
Reviewed-on: https://chromium-review.googlesource.com/c/1298033Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56958}

src/objects/literal-objects.cc

@@ -460,9 +460,6 @@ Handle<ClassBoilerplate> ClassBoilerplate::BuildClassBoilerplate(
   // Initialize class object template.
   //
   static_desc.CreateTemplates(isolate, kMinimumClassPropertiesCount);
-  Handle<DescriptorArray> class_function_descriptors(
-      isolate->native_context()->class_function_map()->instance_descriptors(),
-      isolate);
   STATIC_ASSERT(JSFunction::kLengthDescriptorIndex == 0);
   {
     // Add length_accessor.

test/mjsunit/parallel-compile-tasks.js

@@ -53,3 +53,8 @@ assertEquals(b, 43);
 assertEquals(c, 43);
 var c = (a, b = (function z(){ return a+1; })()) => { return b; };
 assertEquals(c(314), 315);
+
+// http://crbug.com/898076
+(function() {
+  class foo {};
+});  // Don't call IIFE so that it is compiled during idle time