IDEA-114427 Using $this in GString marked as invalid (Identifier or code block expected)

plugins/groovy/src/org/jetbrains/plugins/groovy/lang/lexer/groovy.flex

@@ -22,8 +22,6 @@ import java.util.*;
 
 %%
 
-%{@SuppressWarnings({"UnnecessaryFullyQualifiedName", "FieldCanBeLocal", "UnusedDeclaration", "UnusedAssignment", "AccessStaticViaInstance",
-                    "AssignmentToStaticFieldFromInstanceMethod", "MethodMayBeStatic", "CStyleArrayDeclaration", "UnnecessarySemicolon"}) %}
 %class _GroovyLexer
 %implements FlexLexer, GroovyTokenTypes, TokenType
 %unicode

plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parser/parsing/statements/expressions/primary/CompoundStringExpression.java

@@ -143,10 +143,10 @@ public class CompoundStringExpression implements GroovyElementTypes {
     final PsiBuilder.Marker injection = myBuilder.mark();
     ParserUtils.getToken(myBuilder, mDOLLAR);
 
-    if (mIDENT.equals(myBuilder.getTokenType())) {
+    if (myBuilder.getTokenType() == mIDENT || myBuilder.getTokenType() == kTHIS) {
       PathExpression.parse(myBuilder, myParser);
     }
-    else if (mLCURLY.equals(myBuilder.getTokenType())) {
+    else if (myBuilder.getTokenType() == mLCURLY) {
       OpenOrClosableBlock.parseClosableBlock(myBuilder, myParser);
     }
     else {

plugins/groovy/test/org/jetbrains/plugins/groovy/lang/parser/ExpressionsParsingTest.groovy

@@ -148,6 +148,8 @@ public class ExpressionsParsingTest extends GroovyParsingTestCase {
 
   public void testgstring$ugly_lexer() throws Throwable { doTest(); }
 
+  public void testgstring$this() {doTest()}
+
   public void testmapLiteral() throws Throwable { doTest(); }
 
   public void testnew$arr_decl() throws Throwable { doTest(); }

plugins/groovy/testdata/parsing/groovy/expressions/gstring/this.test

@@ -0,0 +1,19 @@
+print "abc $this.prop test"
+-----
+Groovy script
+  Call expression
+    Reference expression
+      PsiElement(identifier)('print')
+    PsiWhiteSpace(' ')
+    Command arguments
+      Compound Gstring
+        PsiElement(Gstring begin)('"')
+        GrStringContentImpl(GString content element)
+          PsiElement(Gstring content)('abc ')
+        GString injection
+          PsiElement($)('$')
+          Reference expression
+            PsiElement(this)('this')
+        GrStringContentImpl(GString content element)
+          PsiElement(Gstring content)('.prop test')
+        PsiElement(Gstring end)('"')