[wasm] Add a flag --wasm-opt to test optimizations in the WASM pipeline.

src/flag-definitions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file defines all of the flags.  It is separated into different section,
 // for Debug, Release, Logging and Profiling, etc.  To add a new flag, find the
 // correct section, and use one of the DEFINE_ macros, without a trailing ';'.
 //
 // This include does not have a guard, because it is a template-style include,
 // which can be included multiple times in different modes.  It expects to have
@@ skipping 504 matching lines @@
 
 DEFINE_BOOL(wasm_simd_prototype, false,
             "enable prototype simd opcodes for wasm")
 DEFINE_BOOL(wasm_eh_prototype, false,
             "enable prototype exception handling opcodes for wasm")
 DEFINE_BOOL(wasm_mv_prototype, false,
             "enable prototype multi-value support for wasm")
 DEFINE_BOOL(wasm_atomics_prototype, false,
             "enable prototype atomic opcodes for wasm")
 
+DEFINE_BOOL(wasm_opt, false, "enable wasm optimization")
 DEFINE_BOOL(wasm_no_bounds_checks, false,
             "disable bounds checks (performance testing only)")
 DEFINE_BOOL(wasm_no_stack_checks, false,
             "disable stack checks (performance testing only)")
 
 DEFINE_BOOL(wasm_trap_handler, false,
             "use signal handlers to catch out of bounds memory access in wasm"
             " (experimental, currently Linux x86_64 only)")
 DEFINE_BOOL(wasm_guard_pages, false,
             "add guard pages to the end of WebWassembly memory"
@@ skipping 702 matching lines @@
 #undef DEFINE_ALIAS_FLOAT
 #undef DEFINE_ALIAS_ARGS
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA