[wasm] Embedder can control what buffers wasm compilation works on.

src/isolate.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.
 
 #ifndef V8_ISOLATE_H_
 #define V8_ISOLATE_H_
 
 #include <memory>
 #include <queue>
 
@@ skipping 376 matching lines @@
   ISOLATE_INIT_DEBUG_ARRAY_LIST(V)
 
 typedef List<HeapObject*> DebugObjectCache;
 
 #define ISOLATE_INIT_LIST(V)                                                  \
   /* Assembler state. */                                                      \
   V(FatalErrorCallback, exception_behavior, nullptr)                          \
   V(OOMErrorCallback, oom_behavior, nullptr)                                  \
   V(LogEventCallback, event_logger, nullptr)                                  \
   V(AllowCodeGenerationFromStringsCallback, allow_code_gen_callback, nullptr) \
+  V(AllowWasmCompileCallback, allow_wasm_compile_callback, nullptr)           \
+  V(AllowWasmInstantiateCallback, allow_wasm_instantiate_callback, nullptr)   \
   V(ExternalReferenceRedirectorPointer*, external_reference_redirector,       \
     nullptr)                                                                  \
   /* State for Relocatable. */                                                \
   V(Relocatable*, relocatable_top, nullptr)                                   \
   V(DebugObjectCache*, string_stream_debug_object_cache, nullptr)             \
   V(Object*, string_stream_current_security_token, nullptr)                   \
   V(ExternalReferenceTable*, external_reference_table, nullptr)               \
   V(intptr_t*, api_external_references, nullptr)                              \
   V(AddressToIndexHashMap*, external_reference_map, nullptr)                  \
   V(HeapObjectToIndexHashMap*, root_index_map, nullptr)                       \
@@ skipping 1311 matching lines @@
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ISOLATE_H_