[wasm] Remove dead field from WasmInstanceObject

R=titzer@chromium.org

Change-Id: Id9146569af96ee183317e8f571aafff12530767c
Reviewed-on: https://chromium-review.googlesource.com/1063838Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53231}

src/wasm/wasm-objects.h

@@ -309,7 +309,6 @@ class WasmInstanceObject : public JSObject {
   V(kImportedMutableGlobalsBuffersOffset, kPointerSize)                 \
   V(kDebugInfoOffset, kPointerSize)                                     \
   V(kTableObjectOffset, kPointerSize)                                   \
-  V(kFunctionTablesOffset, kPointerSize)                                \
   V(kImportedFunctionInstancesOffset, kPointerSize)                     \
   V(kImportedFunctionCallablesOffset, kPointerSize)                     \
   V(kIndirectFunctionTableInstancesOffset, kPointerSize)                \