Revert "[wasm] Stage wasm-bigint"

This reverts commit bf78435b2c.

Reason for revert: This CL is not what I wanted to land. I mixed up my local branches.

Original change's description:
> [wasm] Stage wasm-bigint
> 
> The implementation on wasm-bigint has been done, as far as I can tell.
> There are no spec tests yet, only an out-dated copy of the original
> spec tests which don't pass anymore. Therefore I disabled all the tests
> for now and created a tracking bug at https://crbug.com/v8/9673.
> 
> R=​adamk@chromium.org
> 
> Bug: v8:7741, v8:9673
> Change-Id: I015846cc6008ad266402b6835e634723a1a076da
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1781050
> Commit-Queue: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63541}

TBR=adamk@chromium.org,ahaas@chromium.org

Change-Id: I5e8a42ad01200c01446efe4ea50f8ae6fef2c174
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7741, v8:9673
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1784279
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63546}

test/common/wasm/wasm-module-runner.cc

@@ -101,12 +101,6 @@ bool InterpretWasmModuleForTesting(Isolate* isolate,
       case kWasmF64:
         arguments[i] = WasmValue(0.0);
         break;
-      case kWasmAnyRef:
-      case kWasmFuncRef:
-      case kWasmExnRef:
-        arguments[i] =
-            WasmValue(Handle<Object>::cast(isolate->factory()->null_value()));
-        break;
       default:
         UNREACHABLE();
     }

test/fuzzer/wasm-fuzzer-common.cc

@@ -89,12 +89,6 @@ const char* ValueTypeToConstantName(ValueType type) {
       return "kWasmF32";
     case kWasmF64:
       return "kWasmF64";
-    case kWasmAnyRef:
-      return "kWasmAnyRef";
-    case kWasmFuncRef:
-      return "kWasmFuncRef";
-    case kWasmExnRef:
-      return "kWasmExnRef";
     default:
       UNREACHABLE();
   }