[heap] Re-allow RO_SPACE sharing with pointer compression

Remove a spurious assert probably introduced by a bad merge that
disallowed RO_SPACE sharing when pointer compression is enabled.

Change-Id: I8a59a242667252dcbb098e5be405ac67a4e01a3d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2445877
Auto-Submit: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70290}

BUILD.gn

@@ -349,10 +349,6 @@ if (v8_enable_shared_ro_heap && v8_enable_pointer_compression) {
 assert(!v8_use_multi_snapshots || !v8_control_flow_integrity,
        "Control-flow integrity does not support multisnapshots")
 
-assert(
-    !v8_enable_pointer_compression || !v8_enable_shared_ro_heap,
-    "Pointer compression is not supported with shared read-only heap enabled")
-
 assert(!v8_enable_heap_sandbox || v8_enable_pointer_compression,
        "V8 Heap Sandbox requires pointer compression")