fix(selectors): resolve text to the innermost match and scan the root in both forms

an element's text is its whole subtree's text on web and on ios, so every ancestor of a matching element matched too, up to the root. a match a descendant also makes is now dropped, in internal/hierarchy, in the chrome xpath translation and in the page-side web runtime, so all three resolvers name the same element. a raw attribute now matches on a substring (exact for true/false) the way the docs describe, and tree-level FindBySelector considers the root, so ax.find("id:page") and ax.find({id: "page"}) agree.

internal/driver/chrome/translate_test.go

@@ -12,10 +12,26 @@ func TestTranslateStringSelector_KnownKeys(t *testing.T) {
 		{"resource-id:account-name", `[id="account-name"]`, false},
 		{"class:btn-primary", `[class~="btn-primary"]`, false},
 		{"tag:button", `button`, false},
-		{"text:Sign in", `//*[normalize-space(text())="Sign in"]`, true},
-		{`text:Say "hi"`, `//*[normalize-space(text())='Say "hi"']`, true},
-		{`text:it's`, `//*[normalize-space(text())="it's"]`, true},
-		{`text:it's "fine"`, `//*[normalize-space(text())=concat("it's ", '"', "fine", '"', "")]`, true},
+		{
+			"text:Sign in",
+			`//*[contains(normalize-space(.), "Sign in") and not(.//*[contains(normalize-space(.), "Sign in")])]`,
+			true,
+		},
+		{
+			`text:Say "hi"`,
+			`//*[contains(normalize-space(.), 'Say "hi"') and not(.//*[contains(normalize-space(.), 'Say "hi"')])]`,
+			true,
+		},
+		{
+			`text:it's`,
+			`//*[contains(normalize-space(.), "it's") and not(.//*[contains(normalize-space(.), "it's")])]`,
+			true,
+		},
+		{
+			`text:it's "fine"`,
+			`//*[contains(normalize-space(.), concat("it's ", '"', "fine", '"', "")) and not(.//*[contains(normalize-space(.), concat("it's ", '"', "fine", '"', ""))])]`,
+			true,
+		},
 		// desc also accepts an iOS merged label, the way internal/hierarchy does.
 		{"desc:logout", `:is([aria-label="logout"], [aria-label^="logout, "])`, false},
 		{"label:logout", `[aria-label="logout"]`, false},
@@ -47,8 +63,21 @@ func TestTranslateStringSelector_UnknownPrefixPassesThrough(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if got != `[role="button"]` {
-		t.Errorf("unknown prefix should map to attribute selector, got %q", got)
+	if got != `[role*="button"]` {
+		t.Errorf(
+			"unknown prefix should map to a substring attribute selector, got %q",
+			got,
+		)
+	}
+	got, _, err = TranslateStringSelector("aria-expanded:true")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != `[aria-expanded="true"]` {
+		t.Errorf(
+			"a boolean value should map to an exact attribute selector, got %q",
+			got,
+		)
 	}
 }