Don't reuse fileModifiedMap from existing context

This causes changes in template files to be ignored on the second build.

src/jit/lib/setupContextUtils.js

@@ -565,8 +565,7 @@ export function getContext(
           )
         )
       ),
-    // Carry over the existing modified map if we have one.
-    fileModifiedMap: new Map(existingContext ? existingContext.fileModifiedMap : undefined),
+    fileModifiedMap: new Map(),
     // ---
     ruleCache: new Set(), // Hit
     classCache: new Map(), // Hit
@@ -582,11 +581,6 @@ export function getContext(
     stylesheetCache: null, // Hit
   }
 
-  if (!existingContext) {
-    // If we didn't have an existing modified map then populate it now.
-    trackModified([...contextDependencies], context)
-  }
-
   // ---
 
   // Update all context tracking state