PreParsing inner functions: Make inner functions less lazy.

Especially, make non-declaration type inner functions eagerly
parsed. Then we still have a chance to compile them eagerly if we see ()
after the function.

BUG=v8:5501

Review-Url: https://codereview.chromium.org/2583843002
Cr-Commit-Position: refs/heads/master@{#41762}

src/flag-definitions.h

@@ -855,6 +855,9 @@ DEFINE_BOOL(allow_natives_syntax, false, "allow natives syntax")
 DEFINE_BOOL(trace_parse, false, "trace parsing and preparsing")
 DEFINE_BOOL(trace_preparse, false, "trace preparsing decisions")
 DEFINE_BOOL(lazy_inner_functions, true, "enable lazy parsing inner functions")
+DEFINE_BOOL(aggressive_lazy_inner_functions, false,
+            "even lazier inner function parsing")
+DEFINE_IMPLICATION(aggressive_lazy_inner_functions, lazy_inner_functions)
 
 // simulator-arm.cc, simulator-arm64.cc and simulator-mips.cc
 DEFINE_BOOL(trace_sim, false, "Trace simulator execution")

src/parsing/parser.cc

@@ -2612,11 +2612,18 @@ FunctionLiteral* Parser::ParseFunctionLiteral(
   // will migrate unresolved variable into a Scope in the main Zone.
   // TODO(marja): Refactor parsing modes: simplify this.
   bool use_temp_zone =
-      (FLAG_lazy_inner_functions
+      (FLAG_aggressive_lazy_inner_functions
            ? can_preparse
            : (is_lazy_top_level_function ||
-              (allow_lazy_ && function_type == FunctionLiteral::kDeclaration &&
+              (parse_lazily() &&
+               function_type == FunctionLiteral::kDeclaration &&
                eager_compile_hint == FunctionLiteral::kShouldLazyCompile)));
+
+  DCHECK_IMPLIES(
+      (is_lazy_top_level_function ||
+       (parse_lazily() && function_type == FunctionLiteral::kDeclaration &&
+        eager_compile_hint == FunctionLiteral::kShouldLazyCompile)),
+      can_preparse);
   bool is_lazy_inner_function =
       use_temp_zone && FLAG_lazy_inner_functions && !is_lazy_top_level_function;