[WebAssembly] Be consistent in generating trivial test input files

For each checked-in wasm file, make sure the there is
corresponding .ll file that can be used to regenerate it
if needed.

Add test/Object/Inputs/trivial-object-test.wasm to match other
formats and add some new wasm tests in test/Object.

Differential Revision: https://reviews.llvm.org/D35213

llvm-svn: 307585
diff --git a/llvm/test/Object/Inputs/trivial.ll b/llvm/test/Object/Inputs/trivial.ll
index 37a6bc2..528a713 100644
--- a/llvm/test/Object/Inputs/trivial.ll
+++ b/llvm/test/Object/Inputs/trivial.ll
@@ -1,3 +1,6 @@
+; Input used for generating checked-in binaries (trivial-object-test.*)
+; llc -mtriple=wasm32-unknown-unknown-wasm trivial.ll -filetype=obj -o trivial-object-test.wasm
+
 @.str = private unnamed_addr constant [13 x i8] c"Hello World\0A\00", align 1
 
 define i32 @main() nounwind {