Compare binaryen fuzz-exec to JS VMs (#1856)

The main fuzz_opt.py script compares JS VMs, and separately runs binaryen's fuzz-exec that compares the binaryen interpreter to itself (before and after opts). This PR lets us directly compare binaryen's interpreter output to JS VMs. This found a bunch of minor things we can do better on both sides, giving more fuzz coverage.

To enable this, a bunch of tiny fixes were needed:

*    Add --fuzz-exec-before which is like --fuzz-exec but just runs the code before opts are run, instead of before and after.
*    Normalize double printing (so JS and C++ print comparable things). This includes negative zero in JS, which we never printed properly til now.
*    Various improvements to how we print fuzz-exec logging - remove unuseful things, and normalize the others across JS and C++.
*    Properly legalize the wasm when --emit-js-wrapper (i.e., we will run the code from JS), and use that in the JS wrapper code.

1 files changed, 2 insertions, 5 deletions

diff --git a/test/reduce/imports.wast.txt b/test/reduce/imports.wast.txt
index 6807ffd26..adfd5ff04 100644
--- a/test/reduce/imports.wast.txt
+++ b/test/reduce/imports.wast.txt
@@ -1,10 +1,7 @@
 (module
- (type $0 (func))
- (type $1 (func (result i32)))
- (import "env" "func" (func $fimport$0))
+ (type $0 (func (result i32)))
  (export "x" (func $0))
- (func $0 (; 1 ;) (type $1) (result i32)
-  (call $fimport$0)
+ (func $0 (; 0 ;) (type $0) (result i32)
   (i32.const 5678)
  )
 )