[DevTools] Better heuristic for detecting object literals

third_party/WebKit/LayoutTests/inspector/console/console-eval-object-literal-expected.txt

 Tests that evaluating object literal in the console correctly reported.
 
 {a:1, b:2}
+Evaluating input as an object literal.
 Object {a: 1, b: 2}
 {a:1}
+Evaluating input as an object literal.
 Object {a: 1}
-{var a = 1; eval("{a :1, b:2 }");}
-    VM:1 Uncaught SyntaxError: Unexpected identifier(…)
+{var a = 1; eval("{ a:1, b:2 }");}
+    VM:1 Uncaught SyntaxError: Unexpected token :(…)
 { for (var i = 0; i < 5; ++i); }
-    VM:1 Uncaught SyntaxError: Unexpected token var(…)
+undefined
+{ a: 4 }),({ b: 7 }
+    VM:1 Uncaught SyntaxError: Unexpected token )(…)
+{ let a = 4; a; }
+4
+var foo = 4;
+undefined
+{ a: foo++ }
+Evaluating input as an object literal.
+Object {a: 4}
+foo;
+5