[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/dead-vreg.ll b/llvm/test/CodeGen/WebAssembly/dead-vreg.ll
index 3174cb8..b94a648 100644
--- a/llvm/test/CodeGen/WebAssembly/dead-vreg.ll
+++ b/llvm/test/CodeGen/WebAssembly/dead-vreg.ll
@@ -7,9 +7,7 @@
 
 define void @foo(i32* nocapture %a, i32 %w, i32 %h) {
 ; CHECK-LABEL: foo:
-; CHECK-NEXT: .param i32
-; CHECK-NEXT: .param i32
-; CHECK-NEXT: .param i32
+; CHECK-NEXT: .param i32, i32, i32
 ; CHECK-NEXT: .local i32, i32, i32, i32, i32, i32, i32, i32, i32{{$}}
 entry:
   %cmp.19 = icmp sgt i32 %h, 0