Revert "[heap] Turn on RO_SPACE sharing for pointer compression"

This reverts commit bbecd8d5.

Reason for revert: https://bugs.chromium.org/p/v8/issues/detail?id=10999

Original change's description:
> [heap] Turn on RO_SPACE sharing for pointer compression
>
> Makes the read-only space sharing the default even with pointer
> compression if on Linux, Android or Chrome OS.
>
> This won't have any immediate impact on Chrome since the platform page
> allocator in chrome does not yet support allocation and remapping of
> shared pages.
>
> Bug: v8:10454
> Change-Id: I3bc57080827efe38095a4bb1d02a53518727056a
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2454077
> Auto-Submit: Dan Elphick <delphick@chromium.org>
> Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#70383}

TBR=rmcilroy@chromium.org,delphick@chromium.org

Change-Id: I0e96f6b901adeb5569a545eb24b15fb8d45bf544
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:10454
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2460806Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70396}

BUILD.gn

@@ -350,8 +350,7 @@ if (v8_multi_arch_build &&
   v8_enable_pointer_compression = !v8_enable_pointer_compression
 }
 if (v8_enable_shared_ro_heap == "") {
-  v8_enable_shared_ro_heap =
-      !v8_enable_pointer_compression || (is_linux || is_chromeos || is_android)
+  v8_enable_shared_ro_heap = !v8_enable_pointer_compression
 }
 
 assert(!v8_disable_write_barriers || v8_enable_single_generation,
@@ -366,7 +365,7 @@ assert(v8_current_cpu == "arm64" || !v8_control_flow_integrity,
 if (v8_enable_shared_ro_heap && v8_enable_pointer_compression) {
   assert(
       is_linux || is_chromeos || is_android,
-      "Sharing read-only heap with pointer compression is only supported on Linux/Android/ChromeOS")
+      "Sharing read-only heap with pointer compression is only supported on Linux or Android")
 }
 
 assert(!v8_use_multi_snapshots || !v8_control_flow_integrity,