Simplify should-eager-compile handling

BUG=v8:5209

Review-Url: https://codereview.chromium.org/2428533002
Cr-Commit-Position: refs/heads/master@{#40366}

src/ast/ast.cc

@@ -293,7 +293,6 @@ bool FunctionLiteral::ShouldEagerCompile() const {
 }
 
 void FunctionLiteral::SetShouldEagerCompile() {
-  if (body_ == nullptr) return;
   scope()->set_should_eager_compile();
 }
 

src/ast/scopes.cc

@@ -310,12 +310,11 @@ bool Scope::HasSimpleParameters() {
 }
 
 bool DeclarationScope::ShouldEagerCompile() const {
-  if (!AllowsLazyCompilation()) return true;
-  return !is_lazily_parsed_ && should_eager_compile_;
+  return force_eager_compilation_ || should_eager_compile_;
 }
 
 void DeclarationScope::set_should_eager_compile() {
-  should_eager_compile_ = true;
+  should_eager_compile_ = !is_lazily_parsed_;
 }
 
 void DeclarationScope::set_asm_module() {