[wasm][asm.js] Exclude zero left hand side in arm64 isel.

BUG=641885
R=titzer@chromium.org,rossberg@chromium.org

Review-Url: https://codereview.chromium.org/2620953002
Cr-Commit-Position: refs/heads/master@{#42190}

src/compiler/arm64/instruction-selector-arm64.cc

@@ -1069,6 +1069,7 @@ bool TryEmitBitfieldExtract32(InstructionSelector* selector, Node* node) {
     // OP is >>> or >> and (K & 0x1f) != 0.
     Int32BinopMatcher mleft(m.left().node());
     if (mleft.right().HasValue() && m.right().HasValue() &&
+        (mleft.right().Value() & 0x1f) != 0 &&
         (mleft.right().Value() & 0x1f) == (m.right().Value() & 0x1f)) {
       DCHECK(m.IsWord32Shr() || m.IsWord32Sar());
       ArchOpcode opcode = m.IsWord32Sar() ? kArm64Sbfx32 : kArm64Ubfx32;

test/mjsunit/asm/regress-641885.js

+// Copyright 2017 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.
+
+var __f_2 = (function __f_4() {
+  "use asm";
+  function __f_2(i) {
+    i = i|0;
+    i = i << -2147483648 >> -1073741824;
+    return i|0;
+  }
+  return { __f_2: __f_2 };
+})().__f_2;