Update to the rustfmt in rust 1.31, which is now stable.

lib/codegen/src/isa/registers.rs

@@ -89,7 +89,8 @@ impl RegBank {
                     None
                 }
             }
-        }.and_then(|offset| {
+        }
+        .and_then(|offset| {
             if offset < self.units {
                 Some(offset + self.first_unit)
             } else {

lib/codegen/src/isa/x86/abi.rs

@@ -98,7 +98,8 @@ impl ArgAssigner for Args {
                         RU::r14
                     } else {
                         RU::rsi
-                    } as RegUnit).into()
+                    } as RegUnit)
+                    .into()
                 }
                 // This is SpiderMonkey's `WasmTableCallSigReg`.
                 ArgumentPurpose::SignatureId => return ArgumentLoc::Reg(RU::r10 as RegUnit).into(),