[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}

src/flag-definitions.h

@@ -589,6 +589,7 @@ 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")