[WebAssembly] Emit .param, .result, and .local through MC.

This eliminates one of the main remaining uses of EmitRawText.

llvm-svn: 253878
diff --git a/llvm/test/CodeGen/WebAssembly/f32.ll b/llvm/test/CodeGen/WebAssembly/f32.ll
index 6e6670c..b709d6d 100644
--- a/llvm/test/CodeGen/WebAssembly/f32.ll
+++ b/llvm/test/CodeGen/WebAssembly/f32.ll
@@ -15,8 +15,7 @@
 declare float @llvm.rint.f32(float)
 
 ; CHECK-LABEL: fadd32:
-; CHECK-NEXT: .param f32{{$}}
-; CHECK-NEXT: .param f32{{$}}
+; CHECK-NEXT: .param f32, f32{{$}}
 ; CHECK-NEXT: .result f32{{$}}
 ; CHECK-NEXT: f32.add $push0, $0, $1{{$}}
 ; CHECK-NEXT: return $pop0{{$}}