Simplify ESLint regexes

The leading `.*` served no real purpose here, so we can just discard it.
Likewise, now that we are using ESLint only, we can simplify the regex
from checking for either double- or single-quotes to just check for
double quotes, since that is what ESLint uses.

lib/import_js/importer.rb

@@ -54,7 +54,7 @@ def fix_imports
     def import_all
       @config.refresh
       undefined_variables = run_eslint_command.map do |line|
-        /.*['"]([^'"]+)['"] is not defined/.match(line) do |match_data|
+        /"([^"]+)" is not defined/.match(line) do |match_data|
           match_data[1]
         end
       end.compact.uniq
@@ -73,7 +73,7 @@ def import_all
     def remove_unused_imports
       @config.refresh
       unused_variables = run_eslint_command.map do |line|
-        /.*['"]([^'"]+)['"] is defined but never used/.match(line) do |match_data|
+        /"([^"]+)" is defined but never used/.match(line) do |match_data|
           match_data[1]
         end
       end.compact.uniq

spec/import_js/importer_spec.rb

@@ -1108,7 +1108,7 @@ def self.current_selection=(index)
     context 'when one undefined variable exists' do
       let(:existing_files) { ['bar/foo.jsx'] }
       let(:eslint_result) do
-        "stdin: line 3, col 11, 'foo' is not defined."
+        "stdin: line 3, col 11, \"foo\" is not defined."
       end
 
       it 'imports that variable' do
@@ -1122,7 +1122,7 @@ def self.current_selection=(index)
       context 'when eslint returns other issues' do
         let(:eslint_result) do
           "stdin: line 1, col 1, Use the function form of \"use strict\".\n" \
-          "stdin: line 3, col 11, 'foo' is not defined."
+          "stdin: line 3, col 11, \"foo\" is not defined."
         end
 
         it 'still imports the variable' do
@@ -1154,8 +1154,8 @@ def self.current_selection=(index)
       let(:text) { 'var a = foo + bar;' }
 
       let(:eslint_result) do
-        "stdin: line 3, col 11, 'foo' is not defined.\n" \
-        "stdin: line 3, col 11, 'bar' is not defined."
+        "stdin: line 3, col 11, \"foo\" is not defined.\n" \
+        "stdin: line 3, col 11, \"bar\" is not defined."
       end
 
       it 'imports all variables' do
@@ -1173,10 +1173,10 @@ def self.current_selection=(index)
       let(:text) { 'var a = foo + bar;' }
 
       let(:eslint_result) do
-        "stdin: line 3, col 11, 'foo' is not defined.\n" +
-        "stdin: line 3, col 11, 'foo' is not defined.\n" +
-        "stdin: line 3, col 11, 'foo' is not defined.\n" +
-        "stdin: line 3, col 11, 'bar' is not defined."
+        "stdin: line 3, col 11, \"foo\" is not defined.\n" +
+        "stdin: line 3, col 11, \"foo\" is not defined.\n" +
+        "stdin: line 3, col 11, \"foo\" is not defined.\n" +
+        "stdin: line 3, col 11, \"bar\" is not defined."
       end
 
       it 'imports all variables' do
@@ -1227,7 +1227,7 @@ def self.current_selection=(index)
 bar
       EOS
       let(:eslint_result) do
-        "stdin: line 1, col 4, 'foo' is defined but never used"
+        "stdin: line 1, col 4, \"foo\" is defined but never used"
       end
 
       it 'removes that import' do
@@ -1249,8 +1249,8 @@ def self.current_selection=(index)
       EOS
 
       let(:eslint_result) do
-        "stdin: line 3, col 11, 'foo' is defined but never used\n" \
-        "stdin: line 3, col 11, 'bar' is defined but never used"
+        "stdin: line 3, col 11, \"foo\" is defined but never used\n" \
+        "stdin: line 3, col 11, \"bar\" is defined but never used"
       end
 
       it 'removes all unused imports' do
@@ -1270,7 +1270,7 @@ def self.current_selection=(index)
       EOS
 
       let(:eslint_result) do
-        "stdin: line 3, col 11, 'foo' is defined but never used\n" \
+        "stdin: line 3, col 11, \"foo\" is defined but never used\n" \
       end
 
       it 'removes that variable from the destructured list' do
@@ -1291,7 +1291,7 @@ def self.current_selection=(index)
       EOS
 
       let(:eslint_result) do
-        "stdin: line 3, col 11, 'foo' is defined but never used\n" \
+        "stdin: line 3, col 11, \"foo\" is defined but never used\n" \
       end
 
       it 'removes the whole import' do