[wasm] Enable optimizations for WASM.

This is just a flag flip to enable WASM optimizations.

R=ahaas@chromium.org,bmeurer@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2545463002
Cr-Commit-Position: refs/heads/master@{#41434}

src/flag-definitions.h

@@ -522,7 +522,7 @@ DEFINE_BOOL(wasm_mv_prototype, false,
 DEFINE_BOOL(wasm_atomics_prototype, false,
             "enable prototype atomic opcodes for wasm")
 
-DEFINE_BOOL(wasm_opt, false, "enable wasm optimization")
+DEFINE_BOOL(wasm_opt, true, "enable wasm optimization")
 DEFINE_BOOL(wasm_no_bounds_checks, false,
             "disable bounds checks (performance testing only)")
 DEFINE_BOOL(wasm_no_stack_checks, false,