Fix SDK errors due to inconsistent inheritance of Operator==.

The informal spec for strong mode top level inference
(#28218) says "If there are
multiple overridden/implemented methods, and any two of them have
non-equal types (declared or inferred) for a parameter position which
is being inferred for the overriding method, it is an error."

This CL fixes several SDK errors that arise from this rule.  For
example, the classes _Closure, Function, and Object contained members
declared as follows:

    class _Closure implements Function {
      bool operator ==(other) ...
    }
    class Function {
      bool operator ==(Object other) ...
    }
    class Object {
      bool operator ==(other) ...
    }

The type of Object's operator == was (dynamic) -> bool; the type of
Function's operator == was (Object) -> bool; therefore the type of
_Closure's operator == (which overrides both, since _Closure extends
Object and implements Function) cannot be inferred and must be
specified.

A similar situation exists for _Double and _IntegerImplementation
(both implement num, which declares operator == to have type (Object)
-> bool), and _Uri (which implements Uri, which declares operator ==
to have type (Object) -> bool).

This CL fixes the error by specifying the type explicitly in the
classes _Closure, _Double, _IntegerImplementation, and _Uri.

Change-Id: I91f7ceef8549399d438ba4be8c408493b3f338db
Reviewed-on: https://dart-review.googlesource.com/28100
Reviewed-by: Vyacheslav Egorov <[email protected]>

Author: stereotype441

runtime/lib/double.dart

@@ -54,7 +54,7 @@ class _Double implements double {
 
   double operator -() native "Double_flipSignBit";
 
-  bool operator ==(other) {
+  bool operator ==(Object other) {
     return (other is num) && _equal(other.toDouble());
   }
 

runtime/lib/function.dart

@@ -5,7 +5,7 @@
 // part of "core_patch.dart";
 
 class _Closure implements Function {
-  bool operator ==(other) native "Closure_equals";
+  bool operator ==(Object other) native "Closure_equals";
 
   int get hashCode {
     if (_hash == null) {

runtime/lib/integers.dart

@@ -124,7 +124,7 @@ abstract class _IntegerImplementation implements int {
   bool _greaterThanFromInteger(int other)
       native "Integer_greaterThanFromInteger";
 
-  bool operator ==(other) {
+  bool operator ==(Object other) {
     if (other is num) {
       return other._equalToInteger(this);
     }

runtime/vm/compiler/method_recognizer.h

@@ -158,7 +158,7 @@ namespace dart {
   V(_Double, >=, Double_greaterEqualThan, Bool, 0x4260c184)                    \
   V(_Double, <, Double_lessThan, Bool, 0x365d1eba)                             \
   V(_Double, <=, Double_lessEqualThan, Bool, 0x74b5eb64)                       \
-  V(_Double, ==, Double_equal, Bool, 0x7ec67775)                               \
+  V(_Double, ==, Double_equal, Bool, 0x613492fc)                               \
   V(_Double, +, Double_add, Double, 0x53994370)                                \
   V(_Double, -, Double_sub, Double, 0x3b69d466)                                \
   V(_Double, *, Double_mul, Double, 0x2bb9bd5d)                                \
@@ -225,7 +225,7 @@ namespace dart {
   V(_IntegerImplementation, _greaterThanFromInteger,                           \
     Integer_greaterThanFromInt, Bool, 0x4a50ed58)                              \
   V(_IntegerImplementation, >, Integer_greaterThan, Bool, 0x6599a6e1)          \
-  V(_IntegerImplementation, ==, Integer_equal, Bool, 0x6d56616e)               \
+  V(_IntegerImplementation, ==, Integer_equal, Bool, 0x58abc487)               \
   V(_IntegerImplementation, _equalToInteger, Integer_equalToInteger, Bool,     \
     0x063be842)                                                                \
   V(_IntegerImplementation, <, Integer_lessThan, Bool, 0x365d1eba)             \
@@ -472,7 +472,7 @@ namespace dart {
   V(_Double, >=, Double_greaterEqualThan, 0x4260c184)                          \
   V(_Double, <, Double_lessThan, 0x365d1eba)                                   \
   V(_Double, <=, Double_lessEqualThan, 0x74b5eb64)                             \
-  V(_Double, ==, Double_equal, 0x7ec67775)                                     \
+  V(_Double, ==, Double_equal, 0x613492fc)                                     \
   V(_Double, +, Double_add, 0x53994370)                                        \
   V(_Double, -, Double_sub, 0x3b69d466)                                        \
   V(_Double, *, Double_mul, 0x2bb9bd5d)                                        \
@@ -486,7 +486,7 @@ namespace dart {
   V(_IntegerImplementation, |, Integer_bitOr, 0x22d38a06)                      \
   V(_IntegerImplementation, ^, Integer_bitXor, 0x79078347)                     \
   V(_IntegerImplementation, >, Integer_greaterThan, 0x6599a6e1)                \
-  V(_IntegerImplementation, ==, Integer_equal, 0x6d56616e)                     \
+  V(_IntegerImplementation, ==, Integer_equal, 0x58abc487)                     \
   V(_IntegerImplementation, <, Integer_lessThan, 0x365d1eba)                   \
   V(_IntegerImplementation, <=, Integer_lessEqualThan, 0x74b5eb64)             \
   V(_IntegerImplementation, >=, Integer_greaterEqualThan, 0x4260c184)          \

sdk/lib/core/uri.dart

@@ -2689,7 +2689,7 @@ class _Uri implements Uri {
     return sb.toString();
   }
 
-  bool operator ==(other) {
+  bool operator ==(Object other) {
     if (identical(this, other)) return true;
     if (other is Uri) {
       Uri uri = other;