all: use the indefinite article an in comments

This is a follow up of CL 530120.

src/cmd/go/internal/script/engine.go

@@ -322,7 +322,7 @@ type command struct {
 	background bool     // command should run in background (ends with a trailing &)
 }
 
-// A expectedStatus describes the expected outcome of a command.
+// An expectedStatus describes the expected outcome of a command.
 // Script execution halts when a command does not match its expected status.
 type expectedStatus string
 

src/cmd/go/testdata/script/test_fuzz_limit_dup_entry.txt

@@ -4,7 +4,7 @@ env GOCACHE=$WORK/cache
 
 # FuzzA attempts to cause the mutator to create duplicate inputs that generate
 # new coverage. Previously this would trigger a corner case when the fuzzer
-# had a execution limit, causing it to deadlock and sit in the coordinator
+# had an execution limit, causing it to deadlock and sit in the coordinator
 # loop indefinitely, failing to exit once the limit had been exhausted.
 
 go test -fuzz=FuzzA -fuzztime=100x -parallel=1

src/cmd/go/testdata/script/test_fuzz_minimize_dirty_cov.txt

@@ -1,6 +1,6 @@
 # Test that minimization doesn't use dirty coverage snapshots when it
 # is unable to actually minimize the input. We do this by checking that
-# a expected value appears in the cache. If a dirty coverage map is used
+# an expected value appears in the cache. If a dirty coverage map is used
 # (i.e. the coverage map generated during the last minimization step,
 # rather than the map provided with the initial input) then this value
 # is unlikely to appear in the cache, since the map generated during

src/crypto/ecdh/ecdh.go

@@ -44,7 +44,7 @@ type Curve interface {
 	// selected public keys can cause ECDH to return an error.
 	NewPublicKey(key []byte) (*PublicKey, error)
 
-	// ecdh performs a ECDH exchange and returns the shared secret. It's exposed
+	// ecdh performs an ECDH exchange and returns the shared secret. It's exposed
 	// as the PrivateKey.ECDH method.
 	//
 	// The private method also allow us to expand the ECDH interface with more
@@ -114,7 +114,7 @@ type PrivateKey struct {
 	publicKeyOnce sync.Once
 }
 
-// ECDH performs a ECDH exchange and returns the shared secret. The PrivateKey
+// ECDH performs an ECDH exchange and returns the shared secret. The PrivateKey
 // and PublicKey must use the same curve.
 //
 // For NIST curves, this performs ECDH as specified in SEC 1, Version 2.0,

src/crypto/internal/edwards25519/field/fe_generic.go

@@ -156,7 +156,7 @@ func feMulGeneric(v, a, b *Element) {
 	rr4 := r4.lo&maskLow51Bits + c3
 
 	// Now all coefficients fit into 64-bit registers but are still too large to
-	// be passed around as a Element. We therefore do one last carry chain,
+	// be passed around as an Element. We therefore do one last carry chain,
 	// where the carries will be small enough to fit in the wiggle room above 2⁵¹.
 	*v = Element{rr0, rr1, rr2, rr3, rr4}
 	v.carryPropagate()

src/encoding/xml/marshal.go

@@ -543,7 +543,7 @@ func (p *printer) marshalValue(val reflect.Value, finfo *fieldInfo, startTemplat
 		}
 	}
 
-	// If a empty name was found, namespace is overridden with an empty space
+	// If an empty name was found, namespace is overridden with an empty space
 	if tinfo.xmlname != nil && start.Name.Space == "" &&
 		tinfo.xmlname.xmlns == "" && tinfo.xmlname.name == "" &&
 		len(p.tags) != 0 && p.tags[len(p.tags)-1].Space != "" {