Data: do not create data cache when fetching single property

Closes gh-2554

src/data/Data.js

@@ -72,13 +72,11 @@ Data.prototype = {
 		return cache;
 	},
 	get: function( owner, key ) {
-		var cache = this.cache( owner );
-
 		return key === undefined ?
-			cache :
+			this.cache( owner ) :
 
 			// Always use camelCase key (gh-2257)
-			cache[ jQuery.camelCase( key ) ];
+			owner[ this.expando ] && owner[ this.expando ][ jQuery.camelCase( key ) ];
 	},
 	access: function( owner, key, value ) {
 

test/unit/data.js

@@ -882,3 +882,19 @@ QUnit.test( "Check that the expando is removed when there's no more data", funct
 		}
 	}
 } );
+
+QUnit.test( ".data(prop) does not create expando", function( assert ) {
+	assert.expect( 1 );
+
+	var key,
+		div = jQuery( "<div/>" );
+
+	div.data("foo");
+	assert.equal( false, jQuery.hasData( div[0] ) );
+	// Make sure no expando has been added
+	for ( key in div[ 0 ] ) {
+		if ( /^jQuery/.test( key ) ) {
+			assert.ok( false, "Expando was created on access" );
+		}
+	}
+} );