Reland: [wasm] Enable lazy compilation for asm-wasm pipeline

Original change's description:
> [wasm] Enable lazy compilation for asm-wasm pipeline
> 
> The validate-asm flag now implies lazy compilation.
> 
> R=​titzer@chromium.org, ahaas@chromium.org
> BUG=v8:5991
> 
> Change-Id: I00fb5ddbe13440941a3fafd9175cc9a5d182e15a
> Reviewed-on: https://chromium-review.googlesource.com/451318
> Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Brad Nelson <bradnelson@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#43952}

TBR=bradnelson@chromium.org,hablich@chromium.org,ahaas@chromium.org,clemensh@chromium.org,v8-reviews@googlegroups.com
NOTRY=true
BUG=v8:5991

Change-Id: Icc6ff9ebcd15fdd140d9fca2676ea2634783e6d5
Reviewed-on: https://chromium-review.googlesource.com/456508Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43970}

src/flag-definitions.h

@@ -587,6 +587,7 @@ DEFINE_BOOL(wasm_interpret_all, false,
             "Execute all wasm code in the wasm interpreter")
 DEFINE_BOOL(asm_wasm_lazy_compilation, false,
             "enable lazy compilation for asm-wasm modules")
+DEFINE_IMPLICATION(validate_asm, asm_wasm_lazy_compilation)
 
 // Profiler flags.
 DEFINE_INT(frame_count, 1, "number of stack frames inspected by the profiler")