Ensure locations are always provided, but don't store them yet.

pkg/front_end/lib/src/fasta/analyzer/element_store.dart

Index: pkg/front_end/lib/src/fasta/analyzer/element_store.dart
diff --git a/pkg/front_end/lib/src/fasta/analyzer/element_store.dart b/pkg/front_end/lib/src/fasta/analyzer/element_store.dart
index 2aa783844c1721c59937dc79984f8e3c0a8adf77..0ac5ea12fbe1bb312461c8c215dddfcbe1127495 100644
--- a/pkg/front_end/lib/src/fasta/analyzer/element_store.dart
+++ b/pkg/front_end/lib/src/fasta/analyzer/element_store.dart
@@ -244,7 +244,7 @@ class KernelParameterElement extends MockParameterElement {
 
 /// Both an [Element] and [Builder] to using memory to store local elements in
 /// [ElementStore].
-class AnalyzerLocalVariableElemment extends MockElement with Builder
+class AnalyzerLocalVariableElemment extends MockElement
     implements LocalVariableElement {
   final analyzer.VariableDeclaration variable;
 
@@ -262,7 +262,7 @@ class AnalyzerLocalVariableElemment extends MockElement with Builder
 
 /// Both an [Element] and [Builder] to using memory to store local elements in
 /// [ElementStore].
-class AnalyzerParameterElement extends MockParameterElement with Builder {
+class AnalyzerParameterElement extends MockParameterElement {
   final analyzer.FormalParameter parameter;
 
   AnalyzerParameterElement(this.parameter);