[arm] Enable write-protected code pages.

R=hablich@chromium.org
BUG=chromium:845877

Change-Id: Ia5ede7b5aaa4d5937160b1e0733132c47afeb712
Reviewed-on: https://chromium-review.googlesource.com/c/1400407Reviewed-by: Michael Hablich <hablich@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58658}

src/flag-definitions.h

@@ -708,13 +708,7 @@ DEFINE_BOOL(incremental_marking_wrappers, true,
 DEFINE_BOOL(trace_unmapper, false, "Trace the unmapping")
 DEFINE_BOOL(parallel_scavenge, true, "parallel scavenge")
 DEFINE_BOOL(trace_parallel_scavenge, false, "trace parallel scavenge")
-#if defined(V8_TARGET_ARCH_ARM)
-#define V8_WRITE_PROTECT_CODE_MEMORY_BOOL false
-#else
-#define V8_WRITE_PROTECT_CODE_MEMORY_BOOL true
-#endif
-DEFINE_BOOL(write_protect_code_memory, V8_WRITE_PROTECT_CODE_MEMORY_BOOL,
-            "write protect code memory")
+DEFINE_BOOL(write_protect_code_memory, true, "write protect code memory")
 #ifdef V8_CONCURRENT_MARKING
 #define V8_CONCURRENT_MARKING_BOOL true
 #else