[wasm] Enable async wasm compile on trunk.

Enabling on trunk after having landed change to add flag and disable for
branch.

BUG=None
R=mtrofin@chromium.org,ahaas@chromium.org
LOG=N

Review-Url: https://codereview.chromium.org/2813213004
Cr-Commit-Position: refs/heads/master@{#44655}

src/flag-definitions.h

@@ -534,7 +534,7 @@ DEFINE_BOOL(wasm_disable_structured_cloning, false,
             "disable WASM structured cloning")
 DEFINE_INT(wasm_num_compilation_tasks, 10,
            "number of parallel compilation tasks for wasm")
-DEFINE_BOOL(wasm_async_compilation, false,
+DEFINE_BOOL(wasm_async_compilation, true,
             "enable actual asynchronous compilation for WebAssembly.compile")
 // Parallel compilation confuses turbo_stats, force single threaded.
 DEFINE_VALUE_IMPLICATION(turbo_stats, wasm_num_compilation_tasks, 0)