Test WebAssembly floating point constants.

f64.const does not yet work on 32-bit Intel.

cranelift/filetests/wasm/f32-arith.cton

@@ -9,7 +9,11 @@ isa intel haswell
 
 ; Constants.
 
-; function %f32_const() -> f32
+function %f32_const() -> f32 {
+ebb0:
+    v1 = f32const 0x3.0
+    return v1
+}
 
 ; Unary operations
 

cranelift/filetests/wasm/f64-arith.cton

@@ -1,15 +1,16 @@
 ; Test basic code generation for f64 arithmetic WebAssembly instructions.
 test compile
 
-set is_64bit=0
-isa intel haswell
-
 set is_64bit=1
 isa intel haswell
 
 ; Constants.
 
-; function %f64_const() -> f64
+function %f64_const() -> f64 {
+ebb0:
+    v1 = f64const 0x3.0
+    return v1
+}
 
 ; Unary operations