Revert "Make patch file import declarations apply to the patched library too."

lib/compiler/implementation/elements/elements.dart

Index: lib/compiler/implementation/elements/elements.dart
diff --git a/lib/compiler/implementation/elements/elements.dart b/lib/compiler/implementation/elements/elements.dart
index ad690789f5fbb8c414a1ab6995d0c5cfe0b77fdc..e2dcc2add44cf35966a395936cf764fb7a9585b6 100644
--- a/lib/compiler/implementation/elements/elements.dart
+++ b/lib/compiler/implementation/elements/elements.dart
@@ -386,18 +386,11 @@ class LibraryElement extends CompilationUnitElement {
 class PrefixElement extends Element {
   Map<SourceString, Element> imported;
   Token firstPosition;
-  final CompilationUnitElement patchSource;
 
-  PrefixElement(SourceString prefix, Element enclosing, this.firstPosition,
-                [this.patchSource])
+  PrefixElement(SourceString prefix, Element enclosing, this.firstPosition)
     : imported = new Map<SourceString, Element>(),
       super(prefix, ElementKind.PREFIX, enclosing);
 
-  CompilationUnitElement getCompilationUnit() {
-    if (patchSource !== null) return patchSource;
-    return super.getCompilationUnit();
-  }
-
   lookupLocalMember(SourceString memberName) => imported[memberName];
 
   Type computeType(Compiler compiler) => compiler.types.dynamicType;