Rename HACK_FORCE_TEXT_AUTOSIZING_ON_DESKTOP

LayoutTests/fast/text-autosizing/resources/autosizingTest.js

 function setWindowSizeOverride(width, height) {
     if (window.internals)
         window.internals.settings.setTextAutosizingWindowSizeOverride(width, height);
 }
 
 function setFontScaleFactor(scale) {
     if (window.internals)
         window.internals.settings.setAccessibilityFontScaleFactor(scale);
 }
 
 function initAutosizingTest() {
     if (window.internals) {
         window.internals.settings.setTextAutosizingEnabled(true);
         setWindowSizeOverride(320, 480);
     } else if (window.console && console.warn) {
         console.warn("This test depends on Text Autosizing being enabled. Run with content shell"
                 + "and --dump-render-tree or manually enable Text Autosizing and either use a "
                 + "mobile device with 320px device-width (like Nexus S or iPhone), or define "
-                + "HACK_FORCE_TEXT_AUTOSIZING_ON_DESKTOP.");
+                + "DEBUG_TEXT_AUTOSIZING_ON_DESKTOP.");
     }
 }
 
 // Automatically call init. Users who want a different window size can use setWindowSizeOverride.
 initAutosizingTest();