Support blocks in asm->wasm global section.

The parser can fold together comma separated declarations
into a single block. The AsmWasmBuilder needs to support
this case in order to handle asm.js modules that use this form.

BUG= https://code.google.com/p/v8/issues/detail?id=4203
TEST=mjsunit/asm-wasm
R=aseemgarg@chromium.org,titzer@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/1697423003

Cr-Commit-Position: refs/heads/master@{#34048}

src/wasm/asm-wasm-builder.cc

@@ -110,11 +110,15 @@ class AsmWasmBuilderImpl : public AstVisitor {
         }
       }
     }
-    DCHECK(in_function_);
-    BlockVisitor visitor(this, stmt->AsBreakableStatement(), kExprBlock, false,
-                         static_cast<byte>(stmt->statements()->length()));
-    RECURSE(VisitStatements(stmt->statements()));
-    DCHECK(block_size_ >= 0);
+    if (in_function_) {
+      BlockVisitor visitor(this, stmt->AsBreakableStatement(), kExprBlock,
+                           false,
+                           static_cast<byte>(stmt->statements()->length()));
+      RECURSE(VisitStatements(stmt->statements()));
+      DCHECK(block_size_ >= 0);
+    } else {
+      RECURSE(VisitStatements(stmt->statements()));
+    }
   }
 
   class BlockVisitor {

test/mjsunit/wasm/asm-wasm.js

@@ -1222,6 +1222,26 @@ TestForeignVariables();
 })();
 
 
+(function TestGlobalBlock() {
+  function Module(stdlib, foreign, buffer) {
+    "use asm";
+
+    var x = foreign.x | 0, y = foreign.y | 0;
+
+    function test() {
+      return (x + y) | 0;
+    }
+
+    return {test: test};
+  }
+
+  var m = _WASMEXP_.instantiateModuleFromAsm(
+      Module.toString(), { x: 4, y: 11 });
+  m.__init__();
+  assertEquals(15, m.test());
+})();
+
+
 (function TestComma() {
   function CommaModule() {
     "use asm";