Fix lints: unnecessary_brace_in_string_interp

pkg/analysis_server/lib/src/services/refactoring/extract_method.dart

Index: pkg/analysis_server/lib/src/services/refactoring/extract_method.dart
diff --git a/pkg/analysis_server/lib/src/services/refactoring/extract_method.dart b/pkg/analysis_server/lib/src/services/refactoring/extract_method.dart
index e83082b54c262d65ca6da4146e584a5c5ddba81d..64225fcab0299f739ff60a329a7c6c7377a8d2f6 100644
--- a/pkg/analysis_server/lib/src/services/refactoring/extract_method.dart
+++ b/pkg/analysis_server/lib/src/services/refactoring/extract_method.dart
@@ -219,10 +219,10 @@ class ExtractMethodRefactoringImpl extends RefactoringImpl
   Future<SourceChange> createChange() async {
     SourceChange change = new SourceChange(refactoringName);
     // replace occurrences with method invocation
-    for (_Occurrence occurence in _occurrences) {
-      SourceRange range = occurence.range;
+    for (_Occurrence occurrence in _occurrences) {
+      SourceRange range = occurrence.range;
       // may be replacement of duplicates disabled
-      if (!extractAll && !occurence.isSelection) {
+      if (!extractAll && !occurrence.isSelection) {
         continue;
       }
       // prepare invocation source
@@ -236,7 +236,7 @@ class ExtractMethodRefactoringImpl extends RefactoringImpl
           // single variable assignment / return statement
           if (_returnVariableName != null) {
             String occurrenceName =
-                occurence._parameterOldToOccurrenceName[_returnVariableName];
+                occurrence._parameterOldToOccurrenceName[_returnVariableName];
             // may be declare variable
             if (!_parametersMap.containsKey(_returnVariableName)) {
               if (variableType.isEmpty) {
@@ -272,7 +272,7 @@ class ExtractMethodRefactoringImpl extends RefactoringImpl
             // argument name
             {
               String argumentName =
-                  occurence._parameterOldToOccurrenceName[parameter.id];
+                  occurrence._parameterOldToOccurrenceName[parameter.id];
               sb.write(argumentName);
             }
           }
@@ -307,7 +307,7 @@ class ExtractMethodRefactoringImpl extends RefactoringImpl
         String returnExpressionSource = _getMethodBodySource();
         // closure
         if (_selectionFunctionExpression != null) {
-          declarationSource = '${name}${returnExpressionSource}';
+          declarationSource = '$name$returnExpressionSource';
           if (_selectionFunctionExpression.body is ExpressionFunctionBody) {
             declarationSource += ';';
           }
@@ -333,16 +333,16 @@ class ExtractMethodRefactoringImpl extends RefactoringImpl
           declarationSource += returnExpressionSource;
           if (_returnVariableName != null) {
             declarationSource +=
-                '${prefix}  return ${_returnVariableName};$eol';
+                '$prefix  return $_returnVariableName;$eol';
           }
-          declarationSource += '${prefix}}';
+          declarationSource += '$prefix}';
         }
       }
       // insert declaration
       if (declarationSource != null) {
         int offset = _parentMember.end;
         SourceEdit edit = new SourceEdit(
-            offset, 0, '${eol}${eol}${prefix}${declarationSource}');
+            offset, 0, '$eol$eol$prefix$declarationSource');
         doSourceChange_addElementEdit(change, unitElement, edit);
       }
     }