Implement UnalignedLoad and UnalignedStore in WASM using LoadByte/Shift/Or and StoreByte/Shift/And.

src/compiler/instruction-selector.h

Index: src/compiler/instruction-selector.h
diff --git a/src/compiler/instruction-selector.h b/src/compiler/instruction-selector.h
index 9c1cd4ca0c0736c6deec3931263ae1fb53b3c57e..41d1474397eda2f6098ba600809ec3d0b8e3b26b 100644
--- a/src/compiler/instruction-selector.h
+++ b/src/compiler/instruction-selector.h
@@ -139,6 +139,8 @@ class InstructionSelector final {
   // TODO(sigurds) This should take a CpuFeatures argument.
   static MachineOperatorBuilder::Flags SupportedMachineOperatorFlags();
 
+  static MachineOperatorBuilder::AlignmentRequirements AlignmentRequirements();
+
   // ===========================================================================
   // ============ Architecture-independent graph covering methods. =============
   // ===========================================================================