[wasm] Turn on trap-if by default.

This CL turns on trap-if by default, and it changes the tests so that
traps in the cctests are also tested without trap-if.

R=titzer@chromium.org, clemensh@chromium.org, bradnelson@chromium.org

Review-Url: https://codereview.chromium.org/2647323002
Cr-Original-Commit-Position: refs/heads/master@{#42603}
Committed: https://chromium.googlesource.com/v8/v8/+/01c87ebe70fb569205432597f3105c708bba0fef
Review-Url: https://codereview.chromium.org/2647323002
Cr-Commit-Position: refs/heads/master@{#42688}

src/flag-definitions.h

@@ -558,7 +558,7 @@ DEFINE_BOOL(wasm_guard_pages, false,
             "add guard pages to the end of WebWassembly memory"
             " (experimental, no effect on 32-bit)")
 DEFINE_IMPLICATION(wasm_trap_handler, wasm_guard_pages)
-DEFINE_BOOL(wasm_trap_if, false,
+DEFINE_BOOL(wasm_trap_if, true,
             "enable the use of the trap_if operator for traps")
 DEFINE_BOOL(wasm_code_fuzzer_gen_test, false,
             "Generate a test case when running the wasm-code fuzzer")

test/cctest/wasm/wasm-run-utils.h

@@ -827,9 +827,9 @@ jmp_buf WasmRunnerBase::jump_buffer;
   void RunWasm_##name(WasmExecutionMode execution_mode);                   \
   TEST(RunWasmCompiled_##name) { RunWasm_##name(kExecuteCompiled); }       \
   void RunWasm_##name(WasmExecutionMode execution_mode);                   \
-  TEST(RunWasmCompiledWithTrapIf_##name) {                                 \
+  TEST(RunWasmCompiledWithoutTrapIf_##name) {                              \
     bool trap_if = FLAG_wasm_trap_if;                                      \
-    FLAG_wasm_trap_if = true;                                              \
+    FLAG_wasm_trap_if = false;                                             \
     RunWasm_##name(kExecuteCompiled);                                      \
     FLAG_wasm_trap_if = trap_if;                                           \
   }                                                                        \