Transition to TypeFlags for specific type checks; Optimize logical ops a bit

tests/binaryen/optimize-if-eqz.js

@@ -0,0 +1,19 @@
+var binaryen = require("binaryen");
+
+var mod = new binaryen.Module();
+var funcType = mod.addFunctionType("i", binaryen.i32, [ binaryen.i32 ]);
+var func = mod.addFunction("test", funcType, [],
+  mod.if(
+    mod.i32.eqz(mod.getLocal(0, binaryen.i32)),
+    mod.i32.const(0),
+    mod.getLocal(0, binaryen.i32)
+  )
+);
+mod.addExport("test", "test");
+
+console.log(mod.emitText());
+if (!mod.validate())
+  console.log("-> does not validate");
+
+mod.optimize();
+console.log(mod.emitText());

tests/binaryen/optimize-if-eqz.wast

@@ -0,0 +1,14 @@
+(module
+ (type $i (func (param i32) (result i32)))
+ (memory $0 0)
+ (export "test" (func $test))
+ (func $test (; 0 ;) (type $i) (param $0 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $0)
+   )
+   (i32.const 0)
+   (get_local $0)
+  )
+ )
+)