Bug: tests involving f64 argument or return types may fail

[abelstuker]

The return values of Wasm functions with f64 as their return type are incorrectly parsed. Additionally, f64 arguments to Wasm functions are also incorrectly conversed.

Consider this Wasm module:

(module
  (func (export "get-5-i32") (result i32) (i32.const 5))
  (func (export "get-5-i64") (result i64) (i64.const 5))
  (func (export "get-5-f32") (result f32) (f32.const 5))
  (func (export "get-5-f64") (result f64) (f64.const 5))

  (func (export "check-eq-5-i32") (param i32) (result i32) (i32.eq (local.get 0) (i32.const 5)))
  (func (export "check-eq-5-i64") (param i64) (result i32) (i64.eq (local.get 0) (i64.const 5)))
  (func (export "check-eq-5-f32") (param f32) (result i32) (f32.eq (local.get 0) (f32.const 5)))
  (func (export "check-eq-5-f64") (param f64) (result i32) (f64.eq (local.get 0) (f64.const 5)))
)

When testing these exports, we expect all the getter functions to return the value 5 and all the check functions, when provided with the argument 5, to return 1.

However, this is not what we observe:

      ✔ Get 5 as i32
      ✔ Get 5 as i64
      ✔ Get 5 as f32
      ✖ Get 5 as f64
        Failure: Expected 5 got 0
      ✔ Check if i32 argument is equal to 5
      ✔ Check if i64 argument is equal to 5
      ✔ Check if f32 argument is equal to 5
      ✖ Check if f64 argument is equal to 5
        Failure: Expected 1 got 0

The f64 value getter returns 0 instead of 5 as expected. The f64 argument equality checker fails instead of succeeding as expected.
The tests covering Wasm functions that involve f64 argument or return types incorrectly (may) fail.