[wasm][test] Avoid stack overflow that can happen with spread call to Array.push.

R=rossberg@chromium.org

Bug: 
Change-Id: I2401709b42106c7e325144b53be3c3b3d1ed16c7
Reviewed-on: https://chromium-review.googlesource.com/599874Reviewed-by: Andreas Rossberg <rossberg@chromium.org>
Commit-Queue: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47127}

test/mjsunit/wasm/wasm-module-builder.js

@@ -74,7 +74,7 @@ class Binary extends Array {
     // Emit section length.
     this.emit_u32v(section.length);
     // Copy the temporary buffer.
-    this.push(...section);
+    for (var i = 0; i < section.length; i++) this.push(section[i]);
   }
 }
 
@@ -197,8 +197,9 @@ class WasmModuleBuilder {
   }
 
   addType(type) {
-    // TODO: canonicalize types?
     this.types.push(type);
+    var pl = type.params.length;  // should have params
+    var rl = type.results.length; // should have results
     return this.types.length - 1;
   }