[wasm] Enable WASM by default (--expose-wasm=true).

BUG=chromium:575167
R=rossberg@chromium.org,ahaas@chromium.org,clemensh@chromium.org,bradnelson@chromium.org

Review-Url: https://codereview.chromium.org/2623743003
Cr-Commit-Position: refs/heads/master@{#42197}

src/flag-definitions.h

@@ -497,7 +497,7 @@ DEFINE_NEG_IMPLICATION(minimal, crankshaft)
 DEFINE_NEG_IMPLICATION(minimal, use_ic)
 
 // Flags for native WebAssembly.
-DEFINE_BOOL(expose_wasm, false, "expose WASM interface to JavaScript")
+DEFINE_BOOL(expose_wasm, true, "expose WASM interface to JavaScript")
 DEFINE_INT(wasm_num_compilation_tasks, 10,
            "number of parallel compilation tasks for wasm")
 DEFINE_BOOL(trace_wasm_encoder, false, "trace encoding of wasm code")

test/mjsunit/wasm/no-wasm-by-default.js → test/mjsunit/wasm/wasm-default-setting.js

@@ -2,5 +2,4 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// TODO(titzer): remove this test when WASM ships.
-assertThrows(function() { var g = Wasm; });
+assertEquals("function", typeof WebAssembly.Module);