[wasm][asm.js] Disable asm->wasm for the M57 branch.

BUG=v8:4203
R=hablich@chromium.org

Review-Url: https://codereview.chromium.org/2641983002
Cr-Commit-Position: refs/heads/master@{#42479}

src/flag-definitions.h

@@ -519,7 +519,7 @@ DEFINE_BOOL(wasm_break_on_decoder_error, false,
 DEFINE_BOOL(wasm_loop_assignment_analysis, true,
             "perform loop assignment analysis for WASM")
 
-DEFINE_BOOL(validate_asm, true, "validate asm.js modules before compiling")
+DEFINE_BOOL(validate_asm, false, "validate asm.js modules before compiling")
 DEFINE_IMPLICATION(ignition_staging, validate_asm)
 DEFINE_BOOL(suppress_asm_messages, false,
             "don't emit asm.js related messages (for golden file testing)")