[wasm] Support validation of asm.js modules with != 3 args.

src/ppc/macro-assembler-ppc.cc

 // Copyright 2014 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.
 
 #include <assert.h>  // For assert
 #include <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #if V8_TARGET_ARCH_PPC
 
 #include "src/base/bits.h"
@@ skipping 2749 matching lines @@
 
   // If the expected number of arguments of the runtime function is
   // constant, we check that the actual number of arguments match the
   // expectation.
   CHECK(f->nargs < 0 || f->nargs == num_arguments);
 
   // TODO(1236192): Most runtime routines don't need the number of
   // arguments passed in because it is constant. At some point we
   // should remove this need and make the runtime routine entry code
   // smarter.
-  mov(r3, Operand(num_arguments));
+  if (num_arguments >= 0) {
+    mov(r3, Operand(num_arguments));
+  }
   mov(r4, Operand(ExternalReference(f, isolate())));
   CEntryStub stub(isolate(),
 #if V8_TARGET_ARCH_PPC64
                   f->result_size,
 #else
                   1,
 #endif
                   save_doubles);
   CallStub(&stub);
 }
@@ skipping 2137 matching lines @@
   }
   if (mag.shift > 0) srawi(result, result, mag.shift);
   ExtractBit(r0, dividend, 31);
   add(result, result, r0);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_PPC