Problems reported:

parser/nnbd/error_recovery/abstract_placement:6:9: The modifier 'abstract' should be before the modifier 'final'.
  final abstract int i1;
        ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:7:9: The modifier 'abstract' should be before the modifier 'final'.
  final abstract i2;
        ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:8:13: The modifier 'abstract' should be before the modifier 'covariant'.
  covariant abstract num i3;
            ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:9:13: The modifier 'abstract' should be before the modifier 'covariant'.
  covariant abstract var i4;
            ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:10:9: The modifier 'abstract' should be before the modifier 'final'.
  final abstract i5;
        ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:11:7: The modifier 'abstract' should be before the modifier 'var'.
  var abstract i6;
      ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:12:5: Expected ';' after this.
  C abstract i7;
    ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:12:14: Variables must be declared using the keywords 'const', 'final', 'var' or a type name.
  C abstract i7;
             ^^

parser/nnbd/error_recovery/abstract_placement:16:5: The modifier 'abstract' should be before the modifier 'var'.
var abstract foo;
    ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:16:5: Can't have modifier 'abstract' here.
var abstract foo;
    ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:20:13: The modifier 'required' should be before the modifier 'covariant'.
  covariant required x;
            ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:20:13: Can't have modifier 'required' here.
  covariant required x;
            ^^^^^^^^

parser/nnbd/error_recovery/abstract_placement:20:22: Variables must be declared using the keywords 'const', 'final', 'var' or a type name.
  covariant required x;
                     ^

beginCompilationUnit(abstract)
  beginMetadataStar(abstract)
  endMetadataStar(0)
  beginClassOrNamedMixinApplicationPrelude(abstract)
    handleIdentifier(C, classOrMixinDeclaration)
    handleNoTypeVariables({)
    beginClassDeclaration(abstract, abstract, C)
      handleNoType(C)
      handleClassExtends(null, 1)
      handleClassNoWithClause()
      handleClassOrMixinImplements(null, 0)
      handleClassHeader(abstract, class, null)
      beginClassOrMixinBody(DeclarationKind.Class, {)
        beginMetadataStar(final)
        endMetadataStar(0)
        handleRecoverableError(Message[ModifierOutOfOrder, The modifier 'abstract' should be before the modifier 'final'., Try re-ordering the modifiers., {string: abstract, string2: final}], abstract, abstract)
        beginMember()
          beginFields({)
            handleIdentifier(int, typeReference)
            handleNoTypeArguments(i1)
            handleType(int, null)
            handleIdentifier(i1, fieldDeclaration)
            handleNoFieldInitializer(;)
          endClassFields(abstract, null, null, null, null, final, 1, final, ;)
        endMember()
        beginMetadataStar(final)
        endMetadataStar(0)
        handleRecoverableError(Message[ModifierOutOfOrder, The modifier 'abstract' should be before the modifier 'final'., Try re-ordering the modifiers., {string: abstract, string2: final}], abstract, abstract)
        beginMember()
          beginFields(;)
            handleNoType(abstract)
            handleIdentifier(i2, fieldDeclaration)
            handleNoFieldInitializer(;)
          endClassFields(abstract, null, null, null, null, final, 1, final, ;)
        endMember()
        beginMetadataStar(covariant)
        endMetadataStar(0)
        handleRecoverableError(Message[ModifierOutOfOrder, The modifier 'abstract' should be before the modifier 'covariant'., Try re-ordering the modifiers., {string: abstract, string2: covariant}], abstract, abstract)
        beginMember()
          beginFields(;)
            handleIdentifier(num, typeReference)
            handleNoTypeArguments(i3)
            handleType(num, null)
            handleIdentifier(i3, fieldDeclaration)
            handleNoFieldInitializer(;)
          endClassFields(abstract, null, null, covariant, null, null, 1, covariant, ;)
        endMember()
        beginMetadataStar(covariant)
        endMetadataStar(0)
        handleRecoverableError(Message[ModifierOutOfOrder, The modifier 'abstract' should be before the modifier 'covariant'., Try re-ordering the modifiers., {string: abstract, string2: covariant}], abstract, abstract)
        beginMember()
          beginFields(;)
            handleNoType(var)
            handleIdentifier(i4, fieldDeclaration)
            handleNoFieldInitializer(;)
          endClassFields(abstract, null, null, covariant, null, var, 1, covariant, ;)
        endMember()
        beginMetadataStar(final)
        endMetadataStar(0)
        handleRecoverableError(Message[ModifierOutOfOrder, The modifier 'abstract' should be before the modifier 'final'., Try re-ordering the modifiers., {string: abstract, string2: final}], abstract, abstract)
        beginMember()
          beginFields(;)
            handleNoType(abstract)
            handleIdentifier(i5, fieldDeclaration)
            handleNoFieldInitializer(;)
          endClassFields(abstract, null, null, null, null, final, 1, final, ;)
        endMember()
        beginMetadataStar(var)
        endMetadataStar(0)
        handleRecoverableError(Message[ModifierOutOfOrder, The modifier 'abstract' should be before the modifier 'var'., Try re-ordering the modifiers., {string: abstract, string2: var}], abstract, abstract)
        beginMember()
          beginFields(;)
            handleNoType(abstract)
            handleIdentifier(i6, fieldDeclaration)
            handleNoFieldInitializer(;)
          endClassFields(abstract, null, null, null, null, var, 1, var, ;)
        endMember()
        beginMetadataStar(C)
        endMetadataStar(0)
        beginMember()
          beginFields(;)
            handleIdentifier(C, typeReference)
            handleNoTypeArguments(abstract)
            handleType(C, null)
            handleIdentifier(abstract, fieldDeclaration)
            handleNoFieldInitializer(i7)
            handleRecoverableError(Message[ExpectedAfterButGot, Expected ';' after this., null, {string: ;}], abstract, abstract)
          endClassFields(null, null, null, null, null, null, 1, C, ;)
        endMember()
        beginMetadataStar(i7)
        endMetadataStar(0)
        beginMember()
          beginFields(;)
            handleRecoverableError(MissingConstFinalVarOrType, i7, i7)
            handleNoType(;)
            handleIdentifier(i7, fieldDeclaration)
            handleNoFieldInitializer(;)
          endClassFields(null, null, null, null, null, null, 1, i7, ;)
        endMember()
      endClassOrMixinBody(DeclarationKind.Class, 8, {, })
    endClassDeclaration(abstract, })
  endTopLevelDeclaration(var)
  beginMetadataStar(var)
  endMetadataStar(0)
  beginTopLevelMember(var)
    handleRecoverableError(Message[ModifierOutOfOrder, The modifier 'abstract' should be before the modifier 'var'., Try re-ordering the modifiers., {string: abstract, string2: var}], abstract, abstract)
    handleRecoverableError(Message[ExtraneousModifier, Can't have modifier 'abstract' here., Try removing 'abstract'., {token: abstract}], abstract, abstract)
    beginFields(})
      handleNoType(abstract)
      handleIdentifier(foo, topLevelVariableDeclaration)
      handleNoFieldInitializer(;)
    endTopLevelFields(null, null, null, null, var, 1, var, ;)
  endTopLevelDeclaration(abstract)
  beginMetadataStar(abstract)
  endMetadataStar(0)
  beginClassOrNamedMixinApplicationPrelude(abstract)
    handleIdentifier(Bar, classOrMixinDeclaration)
    handleNoTypeVariables({)
    beginClassDeclaration(abstract, abstract, Bar)
      handleNoType(Bar)
      handleClassExtends(null, 1)
      handleClassNoWithClause()
      handleClassOrMixinImplements(null, 0)
      handleClassHeader(abstract, class, null)
      beginClassOrMixinBody(DeclarationKind.Class, {)
        beginMetadataStar(covariant)
        endMetadataStar(0)
        handleRecoverableError(Message[ModifierOutOfOrder, The modifier 'required' should be before the modifier 'covariant'., Try re-ordering the modifiers., {string: required, string2: covariant}], required, required)
        handleRecoverableError(Message[ExtraneousModifier, Can't have modifier 'required' here., Try removing 'required'., {token: required}], required, required)
        beginMember()
          beginFields({)
            handleRecoverableError(MissingConstFinalVarOrType, x, x)
            handleNoType(required)
            handleIdentifier(x, fieldDeclaration)
            handleNoFieldInitializer(;)
          endClassFields(null, null, null, covariant, null, null, 1, covariant, ;)
        endMember()
      endClassOrMixinBody(DeclarationKind.Class, 1, {, })
    endClassDeclaration(abstract, })
  endTopLevelDeclaration()
endCompilationUnit(3, )